Track management method and apparatus for managing tracks on a storage medium

ABSTRACT

A track management method includes steps of obtaining track information from a play order table having track information entries arranged in a predetermined play order, the track information corresponds to a track to be deleted and points to a track descriptor in a track information table; obtaining the track descriptor, the track descriptor including a decryption key corresponding to the track to be deleted and pointer information that points to one of a plurality of part descriptors in a part information table; advancing the predetermined play order for a subset of the plurality of track information entries that follow the track to be deleted in the predetermined play order; reading the one of a plurality of part descriptors; separating in a file system a data block that is a part of a file specified by part pointer information in the part descriptor from the file managed by the file system and freeing the data block on the file system, the part pointer information pointing to a part of the file that includes a plurality of data blocks; freeing the part descriptor on the file system; and freeing the track descriptor on the file system.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to a track managementmethod and apparatus for functionally expanding a magneto-optical discusable by a conventional mini-disc (MD) system, the expansion being madein such a manner as to maintain compatibility with the conventional MDsystem.

[0003] 2. Discussion of the Background

[0004] The so-called Mini-disc (MD), a 64 mm-across magneto-optical dischoused in a cartridge, has gained widespread acceptance today as astorage medium to and from which digital audio data are recorded andreproduced.

[0005] The MD system adopts ATRAC (Adaptive TRansform Acoustic Coding)as its audio data compression method. ATRAC involves compression-codingaudio data by what is called MDCT (Modified Discrete Cosine Transform).The audio data has been acquired through a predetermined time window.Typically, music data are compressed by ATRAC to one-fifth to one-tenththe original size.

[0006] The MD system utilizes a convolution code called ACIRC (AdvancedCross Interleave Reed-Solomon Code) as its error correction system andEFM (Eight-to-Fourteen Modulation) as its modulation technique. ACIRC isa convolution code that provides dual error correction on C1 and C2sequences (in vertical and oblique directions). The method is used tocarry out a powerful error correction process on sequential data such asaudio data. One disadvantage of ACIRC is that it requires a linkingsector arrangement for data update purposes. ACIRC and EFM are basicallythe same as those employed in a conventional compact disc (CD) system.

[0007] For music data management, the MD system uses U-TOC (User TOC[Table of Contents]). Specifically, a U-TOC area is furnished on aninner side of a recordable area of the disc. For the current MD system,U-TOC constitutes the track (audio track/data track) title sequence andmanagement information that is updated to keep up with the recording ordeletion of such tracks. Under the U-TOC scheme, each track (i.e., partsconstituting each track) is managed in terms of start position, endposition, and mode settings.

[0008] The disc for the MD system is small, inexpensive, and offers goodcharacteristics when used by the system to record or reproduce audiodata. These advantages have enabled the MD system to gain widespreadmarket acceptance.

[0009] As recognized by the present inventors, MD systems have not fullyachieved their potential in the market as they are not compatible withgeneral purpose computers, such as personal computers. Moreover,convention MD systems use different file management schemes than theFile Allocation Table (FAT)-based file systems used in personalcomputers.

[0010] With more general use of personal computers and PC-basednetworking, more and more audio data are distributed over PC-basednetworks. Today, it is common practice for the user of a personalcomputer to use it as an audio server from which to download favoritemusic files to a portable data reproducing apparatus for musicreproduction. As recognized by the present inventors, because theconventional MD system is not fully compatible with personal computers,a new MD system is desirable that would adopt a general-purposemanagement system, such as a FAT (File Allocation Table) system, toenhance PC-compatibility.

[0011] As explained in White, R., “How Computers Work, MillenniumEdition” Que Corporation, pages 146 and 158 for example, 1999, theentire contents of which being incorporated herein by reference, the FATis created by the disk drive on a particular disk sector, such as sector0. The term “FAT” (or “FAT System”) is used generically herein todescribe various PC-based file systems, and is intended to cover thespecific FAT-based file systems used in DOS, VFAT (virtual FAT) used inWindows 95/98, FAT 32 used in Windows 98/ME/2000, as well as NTFS (NTfile system; sometimes New Technology File System) which is the filesystem used by Windows NT operating system, or optionally in Windows2000 operating system, for storing and retrieving files on read/writedisks. NTFS is the Windows NT equivalent of the Windows 95 fileallocation table (FAT) and the OS/2 High Performance File System (HPFS).

[0012] Meanwhile, a higher degree of compatibility with personalcomputers means increased risk of unauthorized copying of copyrightedworks, which in-turn requires better techniques to protect againstunauthorized copying of audio works. One technological way ofreinforcing copyright laws involves encrypting the audio works whenrecorded. It is also desired that music titles and artist names recordedon the disc be managed in a more efficient manner than at present.

[0013] The current MD system uses a disc with a storage capacity ofabout 160 MB, which, as recognized by the present inventors, is notalways sufficient for the user's requirement for data storage. It isthus desired that the storage capacity of a new disc be boosted whileremaining backwards-compatible with the current MD system.

SUMMARY OF THE INVENTION

[0014] It is therefore an object of the present invention to overcomethe above and other deficiencies of the related art and to provide areproducing method, reproducing apparatus, a recording method, andrecording apparatus for efficiently managing audio data through theintegration of the FAT system on MD media. Alternatively, other mediaformats be used as well in light of the teachings of the presentdisclosure.

[0015] While a “summary” of selected aspects of the invention areprovided below, this summary is not intended to be an exhaustive listingof all novel attributes and combination of attributes of the presentinvention. Nor is this summary intended to be construed independent ofthe other aspects of the present disclosure.

[0016] In carrying out the invention and according to one aspectthereof, there is provided a track management method including the stepsof obtaining track information from a play order table having aplurality of track information entries arranged in a predetermined playorder, the track information corresponds to a track to be deleted andpoints to a track descriptor in a track information table; obtaining thetrack descriptor from the track information table, the track descriptorincluding a decryption key corresponding to the track to be deleted andpointer information that points to one of a plurality of partdescriptors in a part information table; advancing the predeterminedplay order for a subset of the plurality of track information entriesthat follow the track to be deleted in the predetermined play order soas to account for a removal of the track to be deleted from thepredetermined play order; reading the one of a plurality of partdescriptors that corresponds to the pointer information in the trackdescriptor; separating in a file system a data block that is a part of afile specified by part pointer information in the part descriptor fromthe file managed by the file system and freeing the data block on thefile system, the part pointer information pointing to a part of the filethat includes a plurality of data blocks; freeing the part descriptor onthe file system; and freeing the track descriptor on the file system.

[0017] A feature of the first aspect of the present invention is thatthe file is managed by a file allocation table (FAT) system in FATcluster units, the method further including the step of separating thedata block associated with the track to be deleted from the file on theFAT system and freeing the data block on the FAT system when the datablock associated with the track to be deleted does not share a FATcluster with a data track associated with another track.

[0018] Another feature of the first aspect of the present invention isthat the inventive method further includes the step of searching theother part descriptor and adjusting the part pointer information thatpoints to another data block after the data block when a middle datablock in a middle of the file is separated from the file and freed onthe FAT system.

[0019] Another feature of the first aspect of the present invention isthat the part pointer information in the part descriptor has a startaddress and an end address pointing to the part of the file, the methodfurther including the step of separating from the file the data block asthe part of the file based on the start address and the end address andfreeing the data block on the FAT system.

[0020] Still another feature of the first aspect of the presentinvention is that method also includes steps of reading a partdescriptor corresponding to the link information when the partdescriptor has link information pointing to a consecutive partdescriptor, and separating from the file a data block associated withthe part pointer information in the part descriptor and freeing the datablock on the FAT system when the part descriptor has link informationpointing to the consecutive part descriptor.

[0021] Yet a further feature of the first aspect of the presentinvention is that the part pointer information is an offset value from abeginning of the file in predetermined data units.

[0022] Even a further feature of the first aspect of the presentinvention is that the part pointer information is one of a clusternumber in a file allocation table system and a physical address of astorage medium.

[0023] Yet a further feature of the first aspect of the presentinvention is that the file comprises audio data.

[0024] According to a second aspect of the present invention, aninventive apparatus is provided that includes first obtaining means forobtaining track information from a play order table having a pluralityof track information entries arranged in a predetermined play order, thetrack information points to a track descriptor in a track informationtable for a track to be deleted; second obtaining means for obtainingthe track descriptor from the track information table, the trackdescriptor including a decryption key corresponding to the track to bedeleted and pointer information that points to one of a plurality ofpart descriptors in a part information table; advancing means foradvancing the predetermined play order of a subset of the plurality oftrack information entries that follow the track to be deleted in thepredetermined play order so as to account for a removal of the track tobe deleted from the predetermined play order; reading means for readingthe one of a plurality of part descriptors that corresponds to thepointer information in the track descriptor; first means for separatingin a file system a data block as a part of a file specified by partpointer information in the part descriptor from the file managed by thefile system and freeing the data block on the file system, the partpointer information pointing to a part of the file having a plurality ofdata blocks; second means for freeing the part descriptor on the filesystem; and third means for freeing the track descriptor on the filesystem.

[0025] A feature of the second aspect of the present invention is thatthe file is managed by a file allocation table (FAT) system in FATcluster units, the first means, when the data block associated with thetrack to be deleted does not share a FAT cluster with a data trackassociated with the other track, separates the data block associatedwith the track to be deleted from the file on the FAT system and freesthe data block on the FAT system.

[0026] A further feature of the second aspect of the present inventionis that it includes adjusting means for, when a data block of a middleof the file is separated from the file and freed on the FAT system,searching the other part descriptor and adjusting the part pointerinformation pointing to a data block after the data block.

[0027] Still a further feature of the second aspect of the presentinvention is that the part pointer information in the part descriptorhas a start address and an end address pointing to the part of the file;the first means for separating from the file the data block as the partof the file based on the start address and the end address and freeingthe data block on the FAT system.

[0028] Yet another feature of the second aspect of the present inventionis that the first means, when the part descriptor has link informationpointing to a consecutive part descriptor, reads a part descriptorcorresponding to the link information, and separates from the file adata block associated with the part pointer information in the partdescriptor and frees the data block on the FAT system.

[0029] An even further feature of the second aspect of the presentinvention is that the part pointer information is an offset value fromthe beginning of the file in predetermined data units. (data block/soundframe) Still another feature of the second aspect of the presentinvention is that the part pointer information is at least one of acluster number in a file allocation table system and a physical addressof a storage medium.

[0030] An even further feature of the first aspect of the presentinvention is that the file comprises audio data.

[0031] According to this invention, a track information file and anaudio data file are generated on a disc serving as the storage medium.These are the files managed by the so-called FAT system.

[0032] The audio data file is a file that accommodates a plurality ofaudio data items. When viewed from the FAT system, the audio data fileappears to be a very large file. The composition of this file is dividedinto parts, so that audio data are handled as a set of such parts.

[0033] The track information file is a file that describes various typesof information for managing the audio data contained in the audio datafile. The track index file is made up of a play order table, aprogrammed play order table, a group information table, a trackinformation table, a part information table, and a name table.

[0034] The play order table indicates the order of audio datareproduction defined by default. As such, the play order table containsinformation representing links to track descriptors corresponding totrack numbers (i.e., music title numbers) in the track informationtable.

[0035] The programmed play order table contains the order of audio datareproduction defined by the individual user. As such, the programmedplay order table describes programmed track information representinglinks to the track descriptors corresponding to the track numbers.

[0036] The group information table describes information about groups. Agroup is defined as a set of one or more tracks having serial tracknumbers, or a set of one or more tracks with programmed serial tracknumbers.

[0037] The track information table describes information about tracksrepresenting music titles. Specifically, the track information table ismade up of track descriptors representing tracks (music titles). Eachtrack descriptor describes a coding system, copyright managementinformation, content decryption key information, pointer informationpointing to the part number serving as the entry to the music title ofthe track in question, an artist name, a title name, original titleorder information, and recording time information about the track inquestion.

[0038] The part information table describes pointers allowing partnumbers to point to actual music title locations. Specifically, the partinformation table is made up of part descriptors corresponding toindividual parts. Entries of part descriptors are designated from thetrack information table. Each part descriptor is composed of a startaddress and an end address of the part in question in the audio datafile, and a link to the next part.

[0039] When audio data are desired to be reproduced from a particulartrack, information about the designated track number is retrieved fromthe play order table. The track descriptor corresponding to the trackfrom which to reproduce the audio data is then acquired.

[0040] Key information is then obtained from the applicable trackdescriptor in the track information table, and the part descriptorindicating the area containing entry data is acquired. From the partdescriptor, access is gained to the location, in the audio data file, ofthe first part containing the desired audio data, and data are retrievedfrom the accessed location. The reproduced data from the location aredecrypted using the acquired key information for audio datareproduction. If the part descriptor has a link to another part, thelinked part is accessed and the above steps are repeated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] These and other objects of the invention will be seen byreference to the description, taken in connection with the accompanyingdrawing, in which:

[0042]FIG. 1 is an explanatory view of a disc for use with anext-generation MD1 system;

[0043]FIG. 2 is an explanatory view of a recordable area on the disc foruse with the next-generation MD1 system;

[0044]FIGS. 3A and 3B are explanatory views of a disc for use with anext-generation MD2 system;

[0045]FIG. 4 is an explanatory view of a recordable area on the disc foruse with the next-generation MD2 system;

[0046]FIG. 5 is an explanatory view of an error-correcting code schemefor use with the next-generation MD1 and MD2 systems;

[0047]FIG. 6 is another explanatory view of the error-correcting codescheme for use with the next-generation MD1 and MD2 systems;

[0048]FIG. 7 is another explanatory view of the error-correcting codescheme for use with the next-generation MD1 and MD2 systems;

[0049]FIG. 8 is a perspective view of a disc portion showing how anaddress signal is generated using wobbles;

[0050]FIG. 9 is an explanatory view of an ADIP signal for use with thecurrent MD system and the next-generation MD1 system;

[0051]FIG. 10 is another explanatory view of the ADIP signal for usewith the current MD system and the next-generation MD1 system;

[0052]FIG. 11 is an explanatory view of an ADIP signal for use with thenext-generation MD2 system;

[0053]FIG. 12 is another explanatory view of the ADIP signal for usewith the next-generation MD2 system;

[0054]FIG. 13 is a schematic view showing relations between the ADIPsignal and frames for the current MD system and the next-generation MD1system;

[0055]FIG. 14 is a schematic view indicating relations between the ADIPsignal and frames for the next-generation MD1 system;

[0056]FIG. 15 is an explanatory view of a control signal for use withthe next-generation MD2 system;

[0057]FIG. 16 is a block diagram of a disc drive unit;

[0058]FIG. 17 is a block diagram of a media drive unit;

[0059]FIG. 18 is a flowchart of steps for initializing a next-generationMD1 disc;

[0060]FIG. 19 is a flowchart of steps for initializing a next-generationMD2 disc;

[0061]FIG. 20 is an explanatory view of a signal recording bitmap;

[0062]FIG. 21 is a flowchart of steps for reading data from a FATsector;

[0063]FIG. 22 is a flowchart of steps for writing data to a FAT sector;

[0064]FIG. 23 is a flowchart of steps in which the disc drive unit alonereads data from a FAT sector;

[0065]FIG. 24 is a flowchart of steps in which the disc drive unit alonewrites data to a FAT sector;

[0066]FIG. 25 is a flowchart of steps for generating a signal recordingbitmap;

[0067]FIG. 26 is another flowchart of steps for generating the signalrecording bitmap;

[0068]FIG. 27 is another flowchart of steps for generating the signalrecording bitmap;

[0069]FIG. 28 is an explanatory view of a first example of an audio datamanagement system;

[0070]FIG. 29 an explanatory view of an audio data file for use with thefirst example of the audio data management system;

[0071]FIG. 30 is an explanatory view of a track index file for use withthe first example of the audio data management system;

[0072]FIG. 31 is an explanatory view of a play order table for use withthe first example of the audio data management system;

[0073]FIG. 32 is an explanatory view of a programmed play order tablefor use with the first example of the audio data management system;

[0074]FIGS. 33A and 33B are explanatory views of a group informationtable for use with the first example of the audio data managementsystem;

[0075]FIGS. 34A and 34B are explanatory views of a track informationtable for use with the first example of the audio data managementsystem;

[0076]FIGS. 35A and 35B are explanatory views of a part informationtable for use with the first example of the audio data managementsystem;

[0077]FIGS. 36A and 36B are explanatory views of a name table for usewith the first example of the audio data management system;

[0078]FIG. 37 is an explanatory view of typical processing performed bythe first example of the audio data management system;

[0079]FIG. 38 is an explanatory view showing how each name slot in thename table is accessed from a plurality of pointers;

[0080]FIGS. 39A and 39B are explanatory views of a process performed bythe first example of the audio data management system to delete partsfrom the audio data file;

[0081]FIG. 40 is an explanatory view of a second example of the audiodata management system;

[0082]FIG. 41 an explanatory view of an audio data file for use with thesecond example of the audio data management system;

[0083]FIG. 42 is an explanatory view of a track index file for use withthe second example of the audio data management system;

[0084]FIG. 43 is an explanatory view of a play order table for use withthe second example of the audio data management system;

[0085]FIG. 44 is an explanatory view of a programmed play order tablefor use with the second example of the audio data management system;

[0086]FIGS. 45A and 45B are explanatory views of a group informationtable for use with the second example of the audio data managementsystem;

[0087]FIGS. 46A and 46B are explanatory views of a track informationtable for use with the second example of the audio data managementsystem;

[0088]FIGS. 47A and 47B are explanatory views of a name table for usewith the second example of the audio data management system;

[0089]FIG. 48 is an explanatory view of typical processing performed bythe second example of the audio data management system;

[0090]FIG. 49 is an explanatory view showing how the second example ofthe audio data management system divides one file data item into aplurality of indexed areas using an index scheme;

[0091]FIG. 50 is an explanatory view depicting how the second example ofthe audio data management system connects tracks using the index scheme;

[0092]FIG. 51 is an explanatory view indicating how the second exampleof the audio data management system connects tracks using anotherscheme;

[0093]FIGS. 52A and 52B are explanatory views sketching how managementauthority is moved between a personal computer and a disc drive unitconnected therewith depending on the type of data to be written to adisc loaded in the drive unit;

[0094]FIGS. 53A, 53B, and 53C are explanatory views illustrating anaudio data check-out procedure;

[0095]FIG. 54 is a schematic view portraying conceptually how thenext-generation MD1 system and the current MD system may coexist in thedisc drive unit;

[0096]FIG. 55 is an external view of a portable disc drive unit;

[0097]FIG. 56 is a flowchart of steps carried out by the disc drive unitin formatting a disc loaded therein;

[0098]FIG. 57 is a flowchart of steps carried out by the disc drive unitin formatting a virgin disc loaded therein;

[0099]FIG. 58 is a flowchart of steps carried out by the disc drive unitin recording audio data to a disc loaded therein; and

[0100]FIG. 59 is a flowchart of steps for switching from the disc formatof the next-generation MD1 system to the disc format of the current MDsystem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0101] The following description is divided into the following 10sections:

[0102] 1. Outline of the recording system

[0103] 2. Discs

[0104] 3. Signal formats

[0105] 4. Structure of the recording/reproducing apparatus

[0106] 5. Initialization of next-generation MD1 and MD2 discs

[0107] 6. First example of the audio data management system

[0108] 7. Second example of the audio data management system

[0109] 8. Operation during connection with the personal computer

[0110] 9. Restrictions on copying of audio data from the disc

[0111] 10. Coexistence of the next-generation MD1 system with thecurrent MD system

[0112] 1. Outline of the Recording System

[0113] The recording/reproducing apparatus according to the presentinvention uses a magneto-optical disc as its storage medium. Thephysical attributes, such as form-factor, of the disc are substantiallysimilar to the disc utilized by so-called MD (Mini-disc) systems.However, data recorded on the disc and how the data is arranged on thedisc differs from a conventional MD. More particularly, the inventiveapparatus employs a FAT (File Allocation Table) system as its filemanagement system for recording or reproducing content data such asaudio data, so that compatibility with existing personal computers isensured. Once again, the term “FAT” (or “FAT System”) is usedgenerically herein to describe various PC-based file systems, and itintended to be descriptive of the specific FAT structure used in DOS,VFAT (virtual FAT) used in Windows 95/98, FAT 32 used in Windows98/ME/2000, as well as NTFS (NT file system; sometimes New TechnologyFile System) which is the file system used by Windows NT operatingsystem, or optionally in Windows 2000 operating system, for storing andretrieving files on a read/write disks. Compared with the conventionalMD system, the recording/reproducing apparatus of the invention has animproved error correction system and an advanced modulation techniquedesigned to boost data storage capacity and to increase data security.Furthermore, the inventive apparatus encrypts content data and takesmeasures to prevent illegal data copying and ensure copyright protectionfor the content data.

[0114] Generally, there are two kinds of specifications, MD1 and MD2,developed by the present inventors for the next-generation MD system.The MD1 specifications involve the use of the same disc (i.e., physicalmedium) as that which is currently used by the existing MD system. TheMD2 specifications adopt a disc which has a same form-factor as, and isidentical externally to the disc of the current MD system, but whichutilizes a magnetic super-resolution (MSR) technique to enhancerecording density in the linear direction, whereby storage capacity isboosted.

[0115] The current MD system utilizes as its storage medium a 64mm-across magneto-optical disc enclosed in a cartridge. The disc is 1.2mm thick and has a center hole 11 mm in diameter. The cartridge measures68 mm by 72 mm by 5 mm.

[0116] The dimensions and shapes of the discs and cartridges are thesame as the next-generation MD1 and MD2 systems. On both the MD1 and MD2discs, the start position of the lead-in area is the same as with thecurrent MD system, i.e., starting at 29 mm.

[0117] It is proposed for the next-generation MD2 system that the trackpitch be in an inclusive range of 1.2 μm through 1.3 μm (e.g., 1.25 μm).For the next-generation MD1 system with its disc structurally identicalto that of the current MD system, the track pitch is set to 1.6 μm. Thebit length is set to 0.44 μm/bit for the next-generation MD1 disc andproposed at 0.16 μm/bit for the MD2 disc. Redundancy is set to 20.50%for both the next-generation MD1 and the next-generation MD2 discs.

[0118] The next-generation MD2 disc is arranged to increase its storagecapacity in linear direction by resorting to the magneticsuper-resolution technique. The MSR technique involves taking advantageof a specific phenomenon on the disc: that a cut-through layer becomesmagnetically neutral when a particular temperature is reached, allowingmagnetic walls that were transferred to a regenerative layer to move insuch a manner that infinitesimal markings are viewed apparently largerunder a beam spot.

[0119] That is, the next-generation MD2 disc is constituted by amagnetic layer acting as a recording layer for recording at least data,by a cut-through layer, and by a magnetic layer for data regeneration,all deposited on a transparent substrate. The cut-through layer servesas a layer that regulates switched connective force. When a specifictemperature is reached, the cut-through layer becomes magneticallyneutral to let the magnetic walls transferred in the recording layer beshifted into the regenerative magnetic layer. This allows infinitesimalmarkings to become visible under the beam spot. For data recording, alaser pulse magnetic field modulation technique is adopted to generateminuscule markings on the disc.

[0120] On the next-generation MD2 disc, grooves are made deeper thanwith a conventional MD disc and their gradient is steeper as well so asto improve de-track margins and to reduce land-induced crosstalk, wobblesignal crosstalk, and focus leaks. Illustratively, the grooves are in aninclusive range of 160 nm through 180 nm deep, the groove gradient is inan inclusive range of 60 through 70 degrees, and the groove width is inan inclusive range of 600 nm through 700 nm on the next-generation MD2disc.

[0121] As part of its optical specifications, the next-generation MD1disc has its laser wavelength λ set to 780 nm and its numerical apertureNA to 0.45 for an objective lens in an optical head. Likewise, thenext-generation MD2 disc has its laser wavelength λ also set to 780 nmand its numerical aperture NA to 0.45 for the objective lens in theoptical head.

[0122] The next-generation MD1 and MD2 systems both adopt the so-calledgroove recording system as their recording scheme. That is, grooves areformed over the disc surface as tracks for recording and reproductionpurposes.

[0123] As its error-correcting code system, the existing MD systemutilizes a convolutional code based on ACIRC (Advanced Cross InterleaveReed-Solomon Code). By contract, the next-generation MD1 and MD2 systemsemploy a block complete code that combines RS-LDC (Reed Solomon-LongDistance Code) with BIS (Burst Indicator Subcode). Using the blockcomplete error-correcting code eliminates the need for linking sectors.Under the error correction scheme combining LDC with BIS, the locationof a burst error that may occur is detected by BIS. The error locationis utilized in getting the LDC code to effect erasure correction.

[0124] Adopted as the addressing system is the so-called wobbled groovesystem whereby a single spiral groove is formed, and both sides of thegroove is flanked by wobbles furnished as address information. This typeof addressing system is called ADIP (Address in Pregroove). The currentMD system and the next-generation MD1 and MD2 systems differ in lineardensity. Whereas the current MD system adopts as its error-correctingcode a convolutional code called ACIRC, the next-generation MD1 and MD2systems are set to use the block complete code combining LDC and BIS. Asa result, the current MD system and the next-generation MD1 and MD2systems differ in redundancy and have different relative positionsbetween ADIP and data. For these reasons, the next-generation MD1 systemwith its physical disc structurally identical to that of the current MDsystem handles the ADIP signal in a manner different from the current MDsystem. The next-generation MD2 system is set to modify its ADIP signalspecifications for better compliance with the next-generation MD2specifications.

[0125] The current MD system adopts EFM (8 to 14 modulation) as itsmodulation system, whereas the next-generation MD1 and MD2 systemsutilize RLL(1, 7)PP (RLL, Run Length Parity Preserve/Prohibit rmtr[repeated minimum transition Limited; PP, runlength]), called the 1-7 ppmodulation system hereinafter. The next-generation MD1 and MD2 systemsuse a Viterbi decoding method as their data detection method, based onpartial response PR(1, 2, 1)ML for the MD1 system and on partialresponse PR(1, −1)ML for the MD2 system.

[0126] The disc driving system adopts either CLV (Constant LinearVelocity) or ZCAV (Zone Constant Angular Velocity). Standard linearvelocity is set to 2.4 m/sec for the next-generation MD1 system and 1.98m/sec for the next-generation MD2 system. With the current MD system,standard linear velocity is set to 1.2 m/sec for 60-min discs and 1.4m/sec for 74-min discs.

[0127] For the next generation MD1 system with its disc structurallyidentical to that of the current MD system, total data storage capacityper disc is about 300 megabytes (on the 80-min disc). Because the 1-7 ppmodulation system is adopted instead of EFM as the modulation system,window margins are changed from 0.5 to 0.666, whereby recording densityis increased by a factor of 1.33. Since the ACIRC system is replaced bythe combination of BIS with LDC as the error correction system, dataefficiency is boosted, whereby recording density is further increased bya factor of 1.48. Overall, with the same disc in use, data storagecapacity is made approximately double that of the current MD system.

[0128] The next-generation MD2 disc utilizing the magneticsuper-resolution technique is further boosted in recording density inthe linear direction; the total data storage capacity amounts to aboutone gigabytes.

[0129] At standard linear velocity, the data rate is set to 4.4megabits/sec for the next-generation MD1 system and 9.8 megabits/sec forthe next-generation MD2 system.

[0130] 2. Discs

[0131]FIG. 1 shows a typical structure of the next-generation MD1 disc.This disc is structurally identical to that of the current MD system.That is, the disc is made up of a dielectric film, a magnetic film,another dielectric film, and a reflective film, deposited on atransparent polycarbonate substrate. The disc surface is covered with aprotective film.

[0132] On the next-generation MD1 disc, as shown in FIG. 1, a lead-inarea on the innermost side (of the recordable area, where “innermost”refers to a radial direction relative to a center of the disc) has aP-TOC (Pre-mastered TOC [Table Of Contents]) area. As a physicalstructure, this area constitutes a pre-mastered area. That is, embossedpits are formed here to record control information and other relatedinformation such as P-TOC information.

[0133] On the outer side, in the radial direction, of the lead-in areaincluding the P-TOC area is a recordable area (where magneto-opticalrecording is possible). This is a recordable as well as reproduciblearea including recording tracks furnished with grooves as their guides.On the inner side of the recordable area is a U-TOC (User TOC) area.

[0134] The U-TOC area is the same in structure as that of the current MDsystem in which disc management information is recorded. What is held inthe U-TOC area is the order of track (audio track/data track) titles andmanagement information written over as needed to keep up with therecording or erasure of such tracks. More specifically, the managementinformation includes start and end positions of tracks (i.e., partsmaking up the tracks) and mode settings.

[0135] An alert track is furnished on the outer side of the U-TOC area.This track contains an alert sound recorded thereon that is activated(audibilized) by the MD player if the disc is loaded into the current MDsystem. The sound indicates a warning that the disc is for use with thenext-generation MD1 system and cannot be used for reproduction with thecurrent system. The remaining portion of the recordable area (shown inmore detail in FIG. 2) is followed in the radial direction by a lead-outarea.

[0136]FIG. 2 shows a typical structure of the recordable area on thenext-generation MD1 disc indicated in FIG. 1. As illustrated in FIG. 2,the beginning of the recordable area (inner side) has the U-TOC area andthe alert track. A region containing the U-TOC area and alert track hasits data recorded in EFM format so that the data may be reproduced bycurrent MD system players. On the outer side of the area of data storedin EFM format is an area where data are recorded in 1-7 pp modulationformat for the next-generation MD1 system. There is a clearance of apredetermined distance called a “guard band” between the area of datarecordings in EFM format on the one hand, and the area of data storagein 1-7 pp modulation format on the other hand. The guard band isintended to prevent malfunction of the current MD player when the latteris loaded with a next-generation MD1 system disc.

[0137] At the beginning of the area of data recordings in 1-7 ppmodulation format (i.e., inner side), there are a DDT (Disc DescriptionTable) area and a reserve track. The DDT area is designed to replacephysically defective regions and includes a unique ID (UID). The UID isunique to each storage medium, typically based on randomly generatednumbers. The reserve track is provided to accommodate information forcontent protection.

[0138] Furthermore, the area of data storage in 1-7 pp modulation formatincludes a FAT (File Allocation Table) area. The FAT area is an areathat allows the FAT system to manage data pursuant to FAT systemcriteria used by general-purpose computers. More specifically, the FATsystem carries out file management based on FAT chains involving both adirectory indicating the entry points of root files and directories, anda FAT table describing FAT cluster link information. Once again, theterm FAT is used in a general sense to refer to a variety of differentfile management schemes employed by PC operating systems.

[0139] The U-TOC area on the next-generation MD1 disc records two kindsof information: an alert track start position, and the start position ofthe area for data storage in 1-7 pp modulation format.

[0140] When a next-generation MD1 disc is loaded into a current MDsystem player, information is read from the U-TOC area of the loadeddisc. The retrieved U-TOC information reveals the alert track position,allowing the alert track to be accessed so that its data will startbeing reproduced. The alert track contains data constituting the alertsound warning that the disc is for the next-generation MD1 system andcannot be used for reproduction with the current system.

[0141] The alert sound may illustratively articulate a message like“This disc cannot be used on this player.” Alternatively, the alertsound may also be a simple beep, tone or other warning signal.

[0142] When a next-generation MD1 disc is loaded into a next-generationMD1 system player, information is read from the U-TOC area of the loadeddisc. The retrieved UTOC information reveals the start position of thearea where data are stored in 1-7 pp modulation format and allows datato be read from the DDT, reserve track, and FAT area. Over the area ofdata storage in 1-7 pp modulation format, data management is effectednot with the U-TOC but with the FAT system.

[0143]FIGS. 3A and 3B show a typical structure of the next-generationMD2 disc. This disc is also made up of a dielectric film, a magneticfilm, another dielectric film, and a reflective film, deposited on atransparent polycarbonate substrate. The disc surface is covered with aprotective film.

[0144] On the next-generation MD2 disc, as depicted in FIG. 3A, thelead-in area on the inner side (in a radial direction) has controlinformation recorded using an ADIP signal. On the MD2 disc, thecurrently-used P-TOC area of embossed pits is replaced by the lead-inarea having control information based on the ADIP signal. The recordablearea starting from outside the lead-in area is a recordable as well asreproducible area that has grooves formed therein as guides forrecording tracks. The recordable area has data recorded in 1-7 ppmodulation format.

[0145] On the next-generation MD2 disc, as indicated in FIG. 3B, themagnetic film is constituted by a magnetic layer 101 acting as arecording layer for recording data, by a cut-through layer 102, and by amagnetic layer 103 for data regeneration, all deposited on thesubstrate. The cut-through layer 102 serves as a layer that regulatesswitched connective force. When a specific temperature is reached, thecut-through layer 102 becomes magnetically neutral to let the magneticwalls transferred in the recording layer 101 to be shifted into theregenerative magnetic layer 103. This allows infinitesimal markings inthe recording layer 101 to be viewed as apparently enlarged under thebeam spot on the regenerative magnetic layer 103.

[0146] Whether a loaded disc is a next-generation MD1 disc or anext-generation MD2 disc can be determined based on the informationretrieved from the lead-in area. Specifically, if P-TOC information inembossed pits is detected from the lead-in area, it means the loadeddisc is a current MD system disc or a next-generation MD1 disc. Ifcontrol information based on the ADIP signal is detected from thelead-in area, with no P-TOC information in embossed pits detected, itmeans the disc in question is a next-generation MD2 disc. However, thismanner of distinguishing the MD1 disc from the MD2 disc is notlimitative of the invention. Alternatively, phase differences in atracking error signal between on-track and off-track modes may beutilized in determining the disc type. As another alternative, the discmay be given a detection hole for disc identification purposes.

[0147]FIG. 4 shows a typical structure of the recordable area on thenext-generation MD2 disc. As illustrated in FIG. 4, the recordable areahas all its data recorded in 1-7 pp modulation format. A DDT area and areserve track are located at the beginning of (i.e., on the inner sideof) the area where data are recorded in 1-7 pp modulation format. TheDDT area is provided to record alternate area management data formanaging alternate areas intended to replace physically defective areas.Moreover, the DDT area includes a management table that manages areplacement area, which includes a recordable area that substitutes forthe physically defective areas. The management table keeps track of thelogical cluster(s) determined to be defective and also keeps tracks ofthe logical cluster(s) in the replacement area assigned to replace thedefective logical clusters. The DDT area also contains the UID mentionedabove. The reserve track stores information for content protectionpurposes.

[0148] A FAT area is also included in the area with its data recorded in1-7 pp modulation format. The FAT area is used by the FAT system formanaging data. The FAT system, in this embodiment, effects datamanagement pursuant to the FAT system criteria applicable togeneral-purpose personal computers.

[0149] No U-TOC area is provided on the next-generation MD2 disc. When anext-generation MD2 disc is loaded into a next-generation MD2 player,data are read from the DDT area, reserve track, and FAT located asdescribed above on the disc. The retrieved data are used for datamanagement by the FAT system.

[0150] A time-consuming initialization process is not needed onnext-generation MD1 and MD2 discs. More specifically, initialization isnot required on these discs except for advance preparation of a DDTarea, a reserve track, and a minimum set of tables including a FATtable. Data may be directly written to the recordable area of an unuseddisc and then read therefrom without recourse to an initializationprocess.

[0151] 3. Signal Formats

[0152] What follows is a description of signal formats for thenext-generation MD1 and MD2 systems. The current MD system utilizes theconvolutional code called ACIRC as its error correction system in whicha 2,352-byte sector corresponding to the data size of a sub-code blockis regarded as an increment of access for read and write operations.Because the convolutional code scheme involves an error-correcting codesequence spanning a plurality of sectors, it is necessary to provide alinking sector between adjacent sectors when data are to be updated. Asits addressing system, the current MD system adopts the wobbled groovescheme called ADIP in which a single spiral groove is formed, and bothsides of the groove are flanked by wobbles furnished as addressinformation. The current MD system optimally arranges the ADIP signalfor gaining access to the 2,352-byte sector.

[0153] The next-generation MD1 and MD2 systems, by contrast, employ ablock complete code scheme that combines LDC with BIS, and regards a64-kilobyte block as an increment of access for read and writeoperations. Linking sectors are not needed by the block complete code.This, however, requires that the next-generation MD1 system utilizingthe disc of the current MD system rearrange the ADIP signal in a mannercomplying with a new recording method. The next-generation MD2 system isset to alter the ADIP signal specifications to comply with thespecifications of the next-generation MD2 system.

[0154]FIGS. 5, 6, and 7 are explanatory views of the error correctionsystem for use with the next-generation MD1 and MD2 systems. This errorcorrection system combines an LDC-based error-correcting code schemeillustrated in FIG. 5, with the BIS scheme shown in FIGS. 6 and 7.

[0155]FIG. 5 depicts a typical structure of a code block in theLDC-based error-correcting code scheme. As shown in FIG. 5, eacherror-correcting code sector is provided with a four-byte errordetection code EDC, and data are laid out two-dimensionally in theerror-correcting code block that is 304 bytes long horizontally and 216bytes long vertically. Each error-correcting code sector is made up oftwo-kilobyte data. As illustrated in FIG. 5, the 304-byte-by-216-byteerror-correcting code block includes 32 error-correcting code sectors oftwo-kilobyte data each. The 32 error-correcting code sectors laid outtwo-dimensionally in the 304-byte-by-216-byte error-correcting codeblock are furnished vertically with a 32 bit error-correctingReed-Solomon parity code.

[0156]FIGS. 6 and 7 depict a typical BIS structure. As shown in FIG. 6,a one-byte BIS is inserted at intervals of 38 bytes of data. One frameis constituted by 152 bytes (38×4) of data, three-byte BIS data, and2.5-byte frame sync data amounting to 157.5 bytes of data.

[0157] As shown in FIG. 7, a BIS block is formed by 496 frames eachstructured as described above. A BIS data code (3×496=1,488 bytes)includes 576-byte user control data, a 144-byte address unit number, anda 768 byte error-correcting code.

[0158] As described, the BIS code has the 768-byte error-correcting codeattached to the 1,488-byte data. This code structure provides areinforced error correction feature. With this BIS code embedded atintervals of 38 bytes of data, the location of any error that may occuris readily detected. The error location is then used as the basis forerasure correction using the LDC code.

[0159] The ADIP signal is recorded as wobbles formed on both sides of asingle spiral groove, as shown in FIG. 8. That is, the ADIP signal isrecorded by having address data frequency-modulated and formed intogroove wobbles in disc material.

[0160]FIG. 9 depicts a typical sector format of the ADIP signal for thenext-generation MD1 system.

[0161] As shown in FIG. 9, each sector of the ADIP signal (ADIP sector)is made up of four-bit sync data, eight high-order bits of an ADIPcluster number, eight low-order bits of the ADIP cluster number, aneight-bit ADIP sector number, and a 14-bit error detection code CRC.

[0162] The sync data constitute a signal of a predetermined pattern usedto detect the beginning of an ADIP sector. Linking sectors are needed bythe current MD system, because this system utilizes convolutionalcoding. The sector numbers for linking use are negative numbers forsectors FCh, FDh, FEh, and FFh (h: hexadecimal). The ADIP sector formatis the same as that of the current MD system, because thenext-generation MD1 system utilizes the same disc used by the current MDsystem.

[0163] The next-generation MD1 system, as shown in FIG. 10, has its ADPcluster structure formed by 36 ADIP sectors ranging from FCh to FFh andfrom 0Fh to 1Fh. And as illustrated in FIG. 10, one ADIP cluster is madeup of data constituting two recording blocks of 64 kilobytes each.

[0164]FIG. 11 depicts an ADIP sector structure for use with thenext-generation MD2 system. This structure contains 16 ADIP sectors, sothat each ADIP sector number can be expressed in four bits. Linkingsectors are not needed by the next-generation MD2 system, because thesystem uses the block complete error-correcting code.

[0165] As shown in FIG. 11, the ADIP sector structure for thenext-generation MD2 system includes four-bit sync data, four high-orderbits of an ADIP cluster number, eight mid-order bits of the ADIP clusternumber, four low-order bits of the ADIP cluster number, a four-bit ADIPsector number, and an 18-bit error-correcting parity code.

[0166] The sync data constitute a signal of a predetermined pattern usedto detect the beginning of an ADIP sector. The ADIP cluster numberconstitutes 16 bites, i.e., high-order four bits, mid-order eight bits,and low-order four bits. Since 16 ADIP sectors make up an ADIP cluster,each ADIP sector number is given in four bits. Whereas the current MDsystem utilizes the 14-bit error-detecting code, the next-generation MD2system employs the 18-bit error-correcting parity code. For thenext-generation MD2 system, as show in FIG. 12, each ADIP cluster isprovided with one recording block of 64 kilobytes.

[0167]FIG. 13 depicts relations between an ADIP cluster and BIS framesfor the next-generation MD1 system.

[0168] As shown in FIG. 10, one ADIP cluster is constituted by 36 ADIPsectors ranging from FC to FF and from 00 to 1F. A recording block of 64kilobytes, which is an increment for read and write operations, is laidout in two portions in each ADIP cluster.

[0169] Each ADIP sector is divided into two parts, i.e., the first-half18 sectors and the second-half 18 sectors as shown in FIG. 13.

[0170] The data in one recording block forming an increment for read andwrite operations are placed in a BIS block made of 496 frames rangingfrom frame 10 to frame 505. The 496-frame data constituting the BISblock are prefixed with a 10-frame preamble ranging from frame 0 toframe 9. The data frames are further suffixed with a six-frame postambleranging from frame 506 to frame 511. A total of 512 frames of data arethus placed in each of the first and the second half of the ADIPcluster, the first half ranging from ADIP sector FCh to ADIP sector 0Dh,the second half ranging from ADIP sector 0Eh to ADIP sector 1Fh. Thepreamble and postamble are provided to protect the data upon linkagewith adjacent recording blocks. The preamble frames are also used fordata PLL settlement, signal amplitude control, and signal offsetcontrol.

[0171] A physical address used to record or reproduce data to or from agiven recording block is designated in two portions: an ADIP cluster,and distinction of either the first half or the second half of thecluster. When a physical address is designated for a write or a readoperation, the ADIP sector is first read from the ADIP signal inquestion. From a reproduced signal of the ADIP sector, the ADIP clusternumber and ADIP sector number are retrieved so as to determine whetherthe first half or the second half of the ADIP cluster is in effect.

[0172]FIG. 14 illustrates relations between an ADIP cluster and BISframes for the next-generation MD2 system. For the next-generation MD2system, as shown in FIG. 12, 16 ADIP sectors constitute one ADIPcluster. Each ADIP cluster is furnished with one recording block of 64kilobytes of data.

[0173] As shown in FIG. 14, the data in one recording block (64kilobytes) constituting an increment for read and write operations areplaced in a BIS block made up of 496 frames ranging from frame 10 toframe 505. The 496-frame data constituting the BIS block are prefixedwith a 10-frame preamble ranging from frame 0 to frame 9. The dataframes are further suffixed with a six-frame postamble ranging fromframe 506 to frame 511. A total of 512 frames of data are placed in theADIP cluster ranging from ADIP sector 0h to ADIP sector Fh.

[0174] The preamble and postamble frames before and after the dataframes are provided to protect the data upon linkage with adjacentrecording blocks. The preamble frames are also used for data PLLsettlement, signal amplitude control, and signal offset control.

[0175] A physical address used to record or reproduce data to or from agiven recording block is designated in the form of an ADIP cluster. Whena physical address is designated for a write or a read operation, theADIP sector is first read from the ADIP signal in question. From areproduced signal of the ADIP sector, the ADIP cluster number is thenretrieved.

[0176] To start writing or reading data to or from the disc of the abovestructure requires using various kinds of control information for laserpower calibration and other purposes. As shown in FIG. 1, thenext-generation MD1 disc has the P-TOC area included in the lead-inarea. Diverse items of control information are acquired from the P-TOCarea.

[0177] A P-TOC area in embossed pits is not provided on thenext-generation MD2 disc; control information is instead recorded usingthe ADIP signal in the lead-in area. Because the next-generation MD2disc utilizes the magnetic super-resolution technique, laser powercontrol is an important factor. For that reason, calibration areas foruse in power control are provided in the lead-in and lead-out areas ofthe next-generation MD2 disc.

[0178]FIG. 15 shows a lead-in/lead-out area structure on thenext-generation MD2 disc. As illustrated in FIG. 15, the lead-in andlead-out areas of the disc have each a power calibration area for laserbeam power control purposes.

[0179] The lead-in area includes a control area that records ADIPcontrol information. The ADIP control information describes disc controldata using the low-order bit area of the ADIP cluster number.

[0180] More specifically, the ADIP cluster number starts at thebeginning of the recordable area and constitutes a negative value in thelead-in area. As shown in FIG. 15, the ADIP sector on thenext-generation MD2 disc is made up of four-bit sync data, eighthigh-order bits of the ADIP cluster number, eight-bit control data(i.e., low-order bits of the ADIP cluster number), a four-bit ADIPsector number, and an 18-bit error-correcting parity code. As depictedin FIG. 15, the eight low-order bits of the ADIP cluster number describecontrol data such as a disc type, magnetic phase, intensity, and readpower.

[0181] The high-order bits of the ADIP cluster number are left intact,which permits detection of the current cluster position with a fairlyhigh degree of accuracy. ADIP sector “0” and ADIP sector “8” allow thelocations of ADIP clusters to be known precisely at predeterminedintervals, because the eight low-order bits of the ADIP cluster numberare left intact.

[0182] How control data are recorded using the ADIP signal is describedin detail in Applicants' Japanese Patent Application No. 2001-123535,filed in the Japanese Patent Office in 2001, the entire contents ofwhich being incorporated herein by reference.

[0183] 4. Structure of the Recording/Reproducing Apparatus

[0184] Described below with reference to FIGS. 16 and 17 is a typicalstructure of a disc drive unit (recording/reproducing apparatus) thatcomplies with discs for recording/reproducing use with thenext-generation MD1 and MD2 systems.

[0185]FIG. 16 shows a disc drive unit 1 that is connectableillustratively with a personal computer 100.

[0186] The disc drive unit 1 includes a media drive unit 2, a memorytransfer controller 3, a cluster buffer memory 4, an auxiliary memory 5,USB (Universal Serial Bus) interfaces 6 and 8, a USB hub 7, a systemcontroller 9, and an audio processing unit 10.

[0187] The media drive unit 2 permits recording and reproduction of datato and from a loaded disc 90. The disc 90 is a next-generation MD1 disc,a next-generation MD2 disc, or a current MD system disc. An internalstructure of the media drive unit 2 will be discussed later withreference to FIG. 17.

[0188] The memory transfer controller 3 controls transfers of write andread data to and from the media drive unit 2.

[0189] Under control of the memory transfer controller 3, the clusterbuffer memory 4 buffers data that are read in increments of recordingblocks from data tracks of the disc 90 by the media drive unit 2.

[0190] The auxiliary memory 5, under control of the memory transfercontroller 3, stores various items of management information and specialinformation retrieved from the disc 90 by the media drive unit 2.

[0191] The system controller 9 provides overall control inside the discdrive unit 1. Furthermore, the system controller 9 controlscommunications with the personal computer 100 connected to the discdrive unit 1.

[0192] More specifically, the system controller 9 is communicativelyconnected to the personal computer 100 via the USB interface 8 and USBhub 7. In this setup, the system controller 9 receives commands such asa write request and a read request from the personal computer 100 andtransmits status information and other necessary information to the PC100.

[0193] Illustratively, when the disc 90 is loaded into the media driveunit 2, the system controller 9 instructs the media drive unit 2 toretrieve management information and others from the disc 90, and causesthe memory transfer controller 3 to place the retrieved managementinformation, etc., into the auxiliary memory 5.

[0194] Given a request from the personal computer 100 for reading acertain FAT sector, the system controller 9 causes the media drive unit2 to read a recording block containing the FAT sector in question. Theretrieved recording block data are written to the cluster buffer memory4 under control of the memory transfer controller 3.

[0195] From the recording block data written in the cluster buffermemory 4, the system controller 9 retrieves the data constituting therequested FAT sector. The retrieved data are transmitted to the personalcomputer 100 through the USB interface 6 and USB hub 7 under control ofthe system controller 9.

[0196] Given a request from the personal computer 100 for writing acertain FAT sector, the system controller 9 causes the media drive unit2 to read the recording block containing the FAT sector in question. Theretrieved recording block is written to the cluster buffer memory 4under control of the memory transfer controller 3.

[0197] The system controller 9 feeds the memory transfer controller 3with the FAT sector data (i.e., write data) coming from the personalcomputer 100 via the USB interface 6. In the cluster buffer memory 4,the corresponding FAT sector data are updated under control of thesystem controller 9.

[0198] The system controller 9 then instructs the memory transfercontroller 3 to transfer from the cluster buffer memory 4 the recordingblock data, with the relevant FAT sector updated therein, to the mediadrive unit 2 as write data. The media drive unit 2 writes the receivedrecording block data to the disc 90 following a data modulation process.

[0199] A switch 50 is connected to the system controller 9. This switch50 is used to set the operation mode of the disc drive unit 1 to eitherthe next-generation MD1 system or the current MD system. In other words,the disc drive unit 1 is capable of writing audio data to the current MDsystem disc 90 in one of two formats: in the format of the current MDsystem, or in the format of the next-generation MD1 system. The switch50 serves to show the user explicitly what operation mode is set on thedisc drive unit 1. While a mechanical switch is shown, an electrical,magnetic or hybrid switch may be used as well.

[0200] The disc drive unit 1 is furnished with a display unit 51 such asan LCD (Liquid Crystal Display). When fed with a display control signalfrom the system controller 9, the display unit 51 may display text dataand simplified icons constituting status information on the disc driveunit 1 as well as user-oriented messages.

[0201] In its input section, the audio processing unit 10 includesillustratively an analog audio signal input part made of a line inputcircuit and a microphone input circuit, an A/D converter, and a digitalaudio data input part. The audio processing unit 10 also includes anATRAC compression encoder/decoder and a compressed data buffer memory.Furthermore, the audio processing unit 10 includes in its output sectiona digital audio data output part, a D/A converter, and an analog audiosignal output part made of a line output circuit and a headphone outputcircuit.

[0202] If the disc 90 is a current MD system disc and if audio tracksare to be recorded to the disc 90, digital audio data (or analog audiosignals) are input to the audio processing unit 10. The input data arelinear PCM digital audio data or analog audio signals, which areconverted to linear PCM audio data through the A/D converter. The linearPCM audio data are then subjected to ATRAC compression encoding beforebeing placed into the buffer memory. The buffered data are then readfrom the memory in a suitably timed manner (i.e., in data incrementsequivalent to ADIP clusters) and transferred to the media drive unit 2.The media drive unit 2 subjects the compressed data thus transferred toan EFM process before writing the modulated data to the disc 90 as audiotracks.

[0203] If the disc 90 is a current MD system disc and if audio tracksare to be reproduced from the disc 90, the media drive unit 2demodulates the reproduced data back to ATRAC-compressed data andtransfers the demodulated data to the audio processing unit 10 throughthe memory transfer controller 3. The audio processing unit 10 subjectsthe received data to ATRAC compression decoding to acquire linear PCMaudio data which are output through the digital audio data output part.Alternatively, the received data are converted by the D/A converter toanalog audio signals, which are output through the line output orheadphone output part.

[0204] The disc drive unit 1 may be connected to the personal computer100 in a manner other than through the USB arrangement. Illustratively,an external interface such as IEEE (Institute of Electrical andElectronics Engineers) 1394 may be utilized for the connection.

[0205] Read and write data are managed using the FAT system. Howconversion is effected between recording blocks and FAT sectors isdiscussed in detail in Applicants' Japanese Patent Application No.2001-289380, filed in the Japanese Patent Office in 2001, the entirecontents of which being incorporated herein by reference.

[0206] Updating a FAT sector, as described above, involves firstaccessing recording block (RB) containing the FAT sector in question andthen reading the recording block data from the disc. The retrieved dataare written to the cluster buffer memory 4 and the FAT sector of thatrecording block is updated therein. With its FAT sector updated, therecording block is written back to the disc from the cluster buffermemory 4.

[0207] The recordable area is not initialized on the next-generation MD1or MD2 disc. This means that if a given recording block has yet to beused upon FAT sector update, an attempt to read the recording block datawill result in a data reproduction error because no RF signal isobtained. With no data retrieved from the disc, the FAT sector cannot beupdated.

[0208] Reading a FAT sector also involves first accessing the recordingblock containing the FAT sector in question and then reading therecording block data from the disc. The retrieved data are written tothe cluster buffer memory 4 so as to extract the target FAT sector datafrom the recording block. Since the recordable area is not initialized,if the recording block in question has yet to be used, the attempt toextract the data will also fail or will result in erroneous datareproduction with no RF signal obtained.

[0209] The failure discussed above is circumvented by determiningwhether the accessed recording block has ever been used in the past. Ifthe recording block is judged unused, the recording block data are notread.

[0210] More specifically, a signal recording bitmap (SRB) is created toindicate whether each of the recording blocks represented by a recordingblock number have ever been used, as shown in FIG. 20. In the signalrecording bitmap, a bit “0” is set for each recording block that hasnever had data written thereto; and a bit “1” is set for the recordingblock that has data written thereto at least once.

[0211]FIG. 21 is a flowchart of steps performed when a personal computerconnected to a disc drive unit compatible with the next-generation MD1and MD2 discs reads data in increments of FAT sectors from the discloaded in the disc drive unit.

[0212] In step S1 of FIG. 21, the computer issues a command to read datafrom a FAT sector, and the number of the recording block containing theFAT sector in question is obtained. The sector number in this case is anabsolute sector number, with number 0 representing the beginning of theuser area on the disc. In step S2, a check is made to see whether theFAT sector has been replaced by an alternate sector.

[0213] If in step S2 the FAT sector is not judged to have been replacedby an alternate sector, this means the target FAT sector is included inthe recording block whose number was obtained in step S1. In that case,step S3 is reached in which the bit (0 or 1) corresponding to therecording block number is acquired from the signal recording bitmap.

[0214] If in step S2 the FAT sector in question is judged to have beenreplaced by an alternate sector, an actual read/write operation is to becarried out on the alternate sector. In that case, step S4 is reached inwhich the recording block number representing the actual alternatesector is obtained from a DDT alternate table. Step S4 is followed bystep S3 in which the bit (0 or 1) corresponding to the number of therecording block containing the alternate sector is acquired from thesignal recording bitmap.

[0215] The signal recording map is structured as shown in FIG. 20. If nodata have yet to be written to a given recording block, the bitcorresponding to that block is illustratively “0”; if data have beenwritten to a recording block at least once, the corresponding bit forthat block is illustratively “1.” Step S3 is followed by step S5 inwhich the signal recording bitmap is referenced to see whether therecording block in question has had data written thereto in the past.

[0216] If in step S5 the bit is judged to be “1” corresponding to therecording block number in question in the signal recording bitmap (i.e.,the recording block has had data written thereto in the past), then stepS6 is reached. In step S6, the recording block data are read from thedisc and written to the cluster buffer memory 4. In step S7, the datacorresponding to the target FAT sector are extracted from inside thecluster buffer memory 4 and output as read data.

[0217] If in step S5 the bit is judged to be “0” corresponding to therecording block number in question in the signal recording bitmap (i.e.,the recording block has had no data written thereto so far), then stepS8 is reached. In step S8, the entire cluster buffer memory 4 is filledwith zeros. Step S8 is followed by step S7 in which the datacorresponding to the target FAT sector are extracted from inside thecluster buffer memory 4 and output as read data.

[0218]FIG. 22 is a flowchart of steps carried out when the personalcomputer connected to the disc drive unit compatible with thenext-generation MD1 and MD2 discs writes data in increments of FATsectors to the disc loaded in the disc drive unit.

[0219] In step S11 of FIG. 22, the computer issues a command to writedata to a FAT sector, and the number of the recording block containingthe FAT sector in question is obtained. The sector number in this caseis also an absolute sector number, with number 0 representing thebeginning of the user area on the disc. In step S12, a check is made tosee whether the FAT sector has been replaced by an alternate sector.

[0220] If in step S12 the FAT sector in question is not judged to havebeen replaced by an alternate sector, that means the target FAT sectoris included in the recording block whose number was obtained in stepS11. In this case, step S13 is reached in which the bit (0 or 1)corresponding to the recording block number is acquired from the signalrecording bitmap.

[0221] If in step S12 the FAT sector is judged to have been replaced byan alternate sector, an actual read/write operation is to be carried outon the alternate sector. In that case, step S14 is reached in which therecording block number representing the actual alternate sector isobtained from the DDT alternate table. Step S14 is followed by step S13in which the bit (0 or 1) corresponding to the number of the recordingblock containing the alternate sector is acquired from the signalrecording bitmap.

[0222] The signal recording map is structured as shown in FIG. 20. If nodata have yet to be written to a given recording block, the bitcorresponding to that block is illustratively “0”; if data have beenwritten to a recording block at least once, the corresponding bit forthat block is illustratively “1.” Step S13 is followed by step S15 inwhich the signal recording bitmap is referenced to see whether therecording block in question has had data written thereto in the past.

[0223] If in step S15 the bit is judged to be “1” corresponding to therecording block number in question in the signal recording bitmap (i.e.,the recording block has had data written thereto in the past), then stepS16 is reached. In step S16, the recording block data are read from thedisc and written to the cluster buffer memory 4. In step S17, the datacorresponding to the target FAT sector in the recording block arereplaced with write data inside the cluster buffer memory 4.

[0224] If in step S15 the bit is judged to be “0” corresponding to therecording block number in question in the signal recording bitmap (i.e.,the recording block has had no data written thereto so far), then stepS18 is reached. In step S18, the entire cluster buffer memory 4 isfilled with zeros. Step S18 is followed by step S17 in which the datacorresponding to the target FAT sector in the recording block arereplaced with the write data inside the cluster buffer memory 4.

[0225] After the data corresponding to the target FAT sector in therecording block of interest are replaced with the write data in stepS17, step S19 is reached. In step S19, the recording block data arewritten to the disc.

[0226] As described, when data are written to or read from a FAT sector,a check is made to see if the recording block containing that FAT sectorhas ever been used. If the recording block is judged unused, data arenot read from the recording block, and the entire cluster buffer memory4 is filled with zeros. This allows the unused recording block to behandled as having an initial value of 0. As a result, no error occurswhen data are written or read in increments of FAT sectors even if therecording block containing the target FAT sector has never been used andan RF signal is not acquired.

[0227] In the preceding examples, data are written to or read from thetarget FAT sector in a setup where the personal computer is connected tothe disc drive unit compatible with the next-generation MD1 and MD2discs. In such cases, the FAT sector is designated by the personalcomputer using an absolute sector number, with number 0 representing thebeginning of the user area. By contrast, if the disc drive unit alone isused to write or read data to or from the target FAT sector on the disc,the FAT sector is identified using a file directory entry and a FATchain, as shown in FIGS. 23 and 24.

[0228]FIG. 23 is a flowchart of steps in which the disc drive unit alonereads data from a FAT sector of a next-generation MD1 or MD2 disc.

[0229] In step S21 of FIG. 23, the relative cluster number of the FATcluster containing the target FAT sector is obtained. In step S22, theabsolute cluster number of the first FAT cluster is acquired from thefile directory entry. In step S23, a FAT table chain is followed fromthe starting absolute cluster number thus acquired, until the absolutecluster number of the target FAT cluster is obtained. In step S24, theabsolute sector number of the target FAT sector is acquired from theabsolute cluster number of the target FAT cluster. With the absolutesector number of the target FAT sector thus acquired, step S25 isreached in which data are read from the FAT sector. The sector datareading process is the same as that shown in FIG. 21.

[0230]FIG. 24 is a flowchart of steps in which the disc drive unit alonewrites data to a FAT sector of a next-generation MD1 or MD2 disc.

[0231] In step S31 of FIG. 24, the relative cluster number of the FATcluster containing the target FAT sector is obtained. In step S32, theabsolute cluster number of the first FAT cluster is acquired from thefile directory entry. In step S33, the FAT table chain is followed fromthe starting absolute cluster number thus acquired, until the absolutecluster number of the target FAT cluster is obtained. In step S34, theabsolute sector number of the target FAT sector is obtained from theabsolute cluster number of the target FAT cluster. With the absolutesector number of the target FAT sector thus acquired, step S35 isreached in which data are written to the FAT sector. The sector datawriting process is the same as that shown in FIG. 22.

[0232] In the preceding examples, the signal recording bitmap shown inFIG. 20 is used to determine whether the recording block containing thetarget FAT sector has ever been used before. The FAT is illustrativelymanaged in increments of 32-kilobyte FAT clusters. Using the FATinformation makes it possible to check whether any given FAT sector hasbeen used in the past. Based on the FAT information, it is possible tocreate a signal recording bitmap showing illustratively whether each ofthe 64-kilobyte recording blocks has already been used at least once.

[0233]FIG. 25 is a flowchart of steps for generating a signal recordingbitmap using FAT information. In step S41 of FIG. 15, with the discloaded, the values representative of the recording blocks in the signalrecording bitmap are all reset to zero. In step S42, the FAT informationis read. In step S43, the first FAT entry is accessed.

[0234] From the first FAT entry to the last, checks are made to seewhether each of the FAT clusters involved has ever been used so far.That bit in the signal recording bitmap, which corresponds to any unusedFAT cluster, is left intact at “0”; those bits in the signal recordingbitmap, which correspond to used FAT clusters, are each set to “1.”

[0235] That is, with the first FAT entry accessed in step S43, step S44is reached in which a check is made to see if the currently checkedentry is the last FAT entry. If in step S44 the currently checked entryis not judged to be the last FAT entry, step S45 is reached. In stepS45, a check is made to see whether the currently checked FAT entry is aused FAT cluster.

[0236] If in step S45 the currently checked FAT entry is judged to be anunused FAT cluster, step S46 is reached in which the next FAT entry isreached. From step S46, control is returned to step S44.

[0237] If in step S45 the currently checked FAT entry is judged to be aused FAT cluster, step S47 is reached in which the number of therecording block containing the FAT cluster in question is obtained. Instep S48, the bit corresponding to the recording block is set to “1” inthe signal recording bitmap. In step S49, the next FAT entry is reached.From step S49, control is returned to step S44.

[0238] Repeatedly performing steps S44 through S49 generates a signalrecording bitmap in which the bits corresponding to unused FAT clustersare left unchanged at “0”! while the bits corresponding to used FATclusters are each set to “1.”

[0239] If in step S44 the currently checked FAT entry is judged to bethe last FAT entry, then step S50 is reached in which the signalrecording bitmap is deemed complete.

[0240] As described, using the FAT information makes it possible tocreate the signal recording bitmap. Depending on the operating system,however, the FAT clusters judged used based on the FAT information maynot signify those with data actually written thereto in the past. Undersuch an operating system, some FAT clusters may be judged already usedbut in fact they are unused.

[0241] The above conflict is avoided by writing the signal recordingbitmap to the disc. As illustrated in FIGS. 2 and 4, the next-generationMD1 and MD2 discs have a reserve track each between the DDT track andthe FAT track. The reserve track may be used to retain a signalrecording bitmap that accommodates signal recording bitmap informationshown in FIG. 20.

[0242] If the location of the track to which to record the signalrecording bitmap is determined in advance by the system, the bitmap canbe accessed directly based on its predetermined location. The DDT trackand FAT track may also be accessed directly if their locations aredetermined beforehand by the system. Obviously, the locations of thesespecial tracks may alternatively be recorded in the management area(U-TOC on the next-generation MD1 disc; control area containingADIP-based control information on the next-generation MD2 disc). Thedata from the DDT track and FAT track are read when the disc is loaded,and are placed into a buffer memory. The data thus retrieved are used asthe basis for generating alternate sector information and FATinformation. These items of information in the buffer memory are updatedwhile the disc is being used. When the disc is ejected, the updatedalternate sector information and FAT information are written back to theDDT track and FAT track. Writing or reading the signal recording bitmapto or from its recording track is done basically the same way as writingor reading the data to or from the DDT track and FAT track.

[0243] When the disc is loaded, the signal recording bitmap informationis read from its recording track and placed into the memory. Every timedata are written anew to a recording block, the corresponding signalrecording bitmap entry is updated in the memory. When the disc isejected, the updated signal recording bitmap is read from the memory andwritten to the signal recording bitmap track on the disc.

[0244]FIG. 26 is a flowchart of steps for reading information from thesignal recording bitmap track. In step S61 of FIG. 26, with the discloaded, information is read from the signal recording bitmap track ofthe disc. In step S62, the information read from the signal recordingbitmap track is written to the memory and turned into a signal recordingbitmap.

[0245]FIG. 27 is a flowchart of steps for writing the signal recordingbitmap back to the signal recording bitmap track on the disc. In thememory, the signal recording bitmap is updated every time data arewritten anew to any recording block.

[0246] In step S71 of FIG. 27, when the disc is ejected, the updatedsignal recording bitmap is read from the memory. In step S72, theupdated signal recording bitmap thus retrieved is written to the signalrecording bitmap track on the disc.

[0247] In its initial state, the information held in the signalrecording bitmap track is all zeros. Upon each use of the disc, thosebits in the signal recording bitmap, which correspond to the recordingblocks subjected to data write operations, are each updated to “1.” Thisinformation in the signal recording bitmap is written back to the signalrecording bitmap track on the disc. Next time the disc is loaded foruse, the information is read from the signal recording bitmap track andturned into a signal recording bitmap in the memory. These steps make itpossible to generate the signal recording bitmap without recourse to theFAT information.

[0248] Described below with reference to FIG. 17 is a typical structureof the media drive unit 2 capable of writing and reading data to andfrom both the data tracks and the audio tracks of the disc.

[0249] As illustrated in FIG. 17, the media drive unit 2 has a turntablethat may accommodate three kinds of discs: a current MD system disc, anext-generation MD1 disc, and a next-generation MD2 disc. The disc 90placed on the turntable is rotated by a spindle motor 29 on a CLV basis.For a write or read operation on the disc 90, an optical head 19 emits alaser beam onto the disc surface.

[0250] For the write operation, the optical head 19 outputs a laser beamat a level high enough to heat the recording track up to the Curietemperature; for the read operation, the optical head 19 outputs a laserbeam at a relative low level sufficient to detect data from thereflected light based on the magnetic Kerr effect. In order to implementthese capabilities, the optical head 19 incorporates a laser diode aslaser outputting means, an optical system made up of a polarization beamsplitter and an objective lens, and a detector arrangement for detectingthe reflected light, not shown. The objective lens in the optical head19 is held illustratively by a dual axis mechanism in both radially andperpendicularly displaceable relation with the disc surface.

[0251] A magnetic head 18 is positioned in symmetrically oppositerelation to the optical head 19 across the disc 90. The magnetic head 18applies to the disc 90 a magnetic field so modulated as to representwrite data. Although not shown, there are a sled motor and a sledmechanism for moving the optical head 19 in its entirety and themagnetic head 18 in the radial direction of the disc.

[0252] The optical head 19 and magnetic head 18 execute a pulse-drivenmagnetic field modulation process to form infinitesimal markings on thenext-generation MD2 disc. On the current MD system disc ornext-generation MD1 disc, the optical head 19 and magnetic head 18 carryout a DC emission magnetic field modulation process.

[0253] The media drive unit 2 also includes a recording processingsection, a reproduction processing section, and a servo section inaddition to the recording/reproducing head section made up of theoptical head 19 and magnetic head 18, and the disc rotation drivesection formed by the spindle motor 29.

[0254] One of three kinds of discs 90 may be loaded: the current MDsystem disc, the next-generation MD1 disc, or the next-generation MD2disc. Linear velocity varies with the disc type. The spindle motor 29 iscapable of rotating each loaded disc 90 at a speed compatible with thedisc type in question. That is, the disc 90 placed on the turntable isrotated at a linear velocity corresponding to one of the three usabledisc types above.

[0255] The recording processing section includes two portions: oneadopting ACIRC for error correction and EFM for data modulation in orderto write error-corrected modulated data to audio tracks on the currentMD system disc, and the other portion utilizing BIS and LDC incombination for error correction and the 1-7 pp modulation for datamodulation so as to write error-corrected modulated data to thenext-generation MD1 or MD2 system disc.

[0256] The reproduction processing section includes two portions: oneadopting EFM for data demodulation and ACIRC for error correction inreproducing data from the current MD system disc, and the other portionutilizing the 1-7 demodulation based on data detection using the partialresponse scheme and Viterbi decoding method for data reproduction fromthe next-generation MD1 or MD2 system disc.

[0257] The reproduction processing section further includes a portionfor decoding ADIP signal-based addresses used by the current MD systemor by the next-generation MD1 system, and a portion for decoding theADIP signal adopted by the next-generation MD2 system.

[0258] Laser emission from the optical head 19 onto the disc 90 producesa reflected light beam representative of information detected from thedisc. The detected information, i.e., a photoelectric current obtainedby a photo detector detecting the reflected laser beam, is sent to an RFamplifier 21.

[0259] The RF amplifier 21 subjects the detected information thusreceived to current-to-voltage conversion, amplification, and matrixcomputation in order to extract reproduced information including areproduced RF signal, a tracking error signal TE, a focus error signalFE, and groove information (ADIP information recorded as track wobbleson the disc 90).

[0260] When data are reproduced from the current MD system disc, thereproduced RF signal obtained by the RF amplifier 21 is processed by anEFM demodulation unit 24 and an ACIRC decoder 25. More specifically, theEFM demodulation unit 24 binarizes the reproduced RF signal into an EFMsignal train before submitting it to EFM demodulation. The demodulatedsignal is subjected to error correction and de-interleave processing bythe ACIRC decoder 25. At this point, ATRAC-compressed data are obtained.

[0261] Upon data reproduction from the current MD system disc, aselector 26 is set to contact B. In that setting, the selector 26 allowsthe demodulated ATRAC-compressed data to be output as the reproduceddata from the disc 90.

[0262] When data are reproduced from the next-generation MD1 or MD2disc, the reproduced RF signal obtained by the RF amplifier 21 is fed toan RLL(1-7)PP demodulation unit 22 and an RS-LDC decoder 23. Morespecifically, given the reproduced RF signal, the RLL(1-7)PPdemodulation unit 22 performs data detection through PR(1, 2, 1)ML orPR(1, 1)ML and Viterbi decoding to acquire an RLL(1-7) code train asreproduced data. The demodulation unit 22 subjects the RLL(1-7) codetrain to RLL(1-7) demodulation. The demodulated data are fed to theRS-LDC decoder 23 for error correction and de-interleave processing.

[0263] Upon data reproduction from the next-generation MD1 or MD2 disc,the selector 26 is set to contact A. The selector 26 in that settingallows the demodulated data to be output as the reproduced data from thedisc 90.

[0264] The tracking error signal TE and focus error signal FE from theRF amplifier 21 are sent to a servo circuit 27. The groove informationfrom the RF amplifier 21 is supplied to an ADIP demodulation unit 30.

[0265] The ADIP demodulation unit 30 submits the received grooveinformation to a band-pass filter to extract the wobble components,before effecting FM demodulation and biphase demodulation to demodulatethe ADIP signal. The demodulated ADIP signal is fed to address decoders32 and 33.

[0266] On the current MD system disc or next-generation MD1 disc, theADIP sector number is eight bits long, as shown in FIG. 9. On thenext-generation MD2 disc, by contrast, the ADIP sector number is fourbits long as illustrated in FIG. 11. The address decoder 32 decodes theADIP address from the current MD system disc or next-generation MD1disc, while the address decoder 33 decodes the ADIP address from thenext-generation MD2 disc.

[0267] The ADIP address decoded by the address decoder 32 or 33 is sentto a drive controller 31. Given the ADIP address, the drive controller31 carries out necessary control processing. The groove information fromthe RF amplifier 21 is also fed to the servo circuit 27 for spindleservo control.

[0268] The servo circuit 27 integrates phase differences between thereceived groove information and a reproduced clock signal (PLL clocksignal in effect upon decoding) to obtain an error signal. Based on theerror signal thus acquired, the servo circuit 27 generates a spindleerror signal for CLV or CAV servo control.

[0269] The servo circuit 27 generates various servo control signals(e.g., tracking control signal, focus control signal, sled controlsignal, and spindle control signal) based on the spindle error signal,on the tracking error signal and focus error signal from the RFamplifier 21, or on a track jump command and an access command from thedrive controller 31. The servo control signals thus generated are outputto a motor driver 28. More specifically, the servo circuit 27 subjectsthe servo error signals and commands to such processes as phasecompensation, gain processing, and target value setting in order togenerate the diverse servo control signals.

[0270] The motor driver 28 generates servo drive signals based on theservo control signals fed from the servo circuit 27. The servo drivesignals generated by the motor driver 28 are made up of dual axis drivesignals for driving the dual axis mechanism (two signals for driving infocusing and tracking directions), a sled motor drive signal for drivingthe sled mechanism, and a spindle motor drive signal for driving thespindle motor 29. These servo drive signals provide focus and trackingcontrol on the disc 90 and CLV or CAV control over the spindle motor 29.

[0271] When audio data are to be recorded to the current MD system disc,a selector 16 is set to contact B. The selector setting allows the ACIRCencoder 14 and EFM modulation unit 15 to function. In this setup, thecompressed data coming from the audio processing unit 10 are subjectedto interleave processing and error correction coding by the ACIRCencoder 14. The output of the ACIRC encoder 14 is submitted to EFMprocessing by the EFM modulation unit 15.

[0272] The EFM-modulated data are fed to a magnetic head driver 17through the selector 16. The magnetic head 18 applies to the disc 90 amagnetic field representative of the EFM-modulated data, whereby thedata are written to audio tracks on the disc 90.

[0273] When audio data are to be recorded to the next-generation MD1 orMD2 disc, the selector 16 is set to contact A. That setting allows anRS-LDC encoder 12 and an RLL(1-7)PP modulation unit 13 to function. Inthis setup, high-density data coming from the memory transfer controller3 are subjected to interleave processing and RS-LDC-based errorcorrection coding by the RS-LDC encoder 12. The output of the RS-LDCencoder 12 is submitted to RLL(1-7) modulation by the RLL(1-7)PPmodulation unit 13.

[0274] The write data in the form of an RLL(1-7) code train are fed tothe magnetic head driver 17 through the selector 16. The magnetic head18 applies to the disc 90 a magnetic field representative of themodulated data, whereby the data are written to audio tracks on the disc90.

[0275] The purpose of a laser driver/APC 20 is twofold: to cause thelaser diode to emit a laser beam during the read and write operations asdescribed above, and to effect so-called APC (Automatic Laser PowerControl).

[0276] Although not shown, a detector for monitoring the laser powerlevel is incorporated in the optical head 19. A monitor signal from thedetector is fed back to the laser driver/APC 20. The laser driver/APC 20compares the current laser power level acquired as the monitor signalwith an established laser power level to find an error difference. Bygetting that error difference reflected in the laser drive signal, thelaser driver 20 keeps the laser power from the laser diode stabilized atthe established level.

[0277] Two laser power levels, i.e., a read laser power level and awrite laser power level, are set by the drive controller 31 to registersinside the laser driver/APC 20.

[0278] Under control of the system controller 9, the drive controller 31sees to it that the controlled operations described above (access, servooperations, data write operation, and data read operation) are properlycarried out.

[0279] In FIG. 17, portions A and B enclosed by dashed lines may each beimplemented as a single-chip circuit part.

[0280] 5. Initialization of Next-Generation MD1 and MD2 Discs

[0281] On both the next-generation MD1 disc and the next-generation MD2disc, a unique ID (UID) is recorded in addition to the FAT for securitymanagement purposes as mentioned earlier. On each next-generation MD1 orMD2 disc, in principle, the UID is recorded to a predetermined locationsuch as in the lead-in area before the disc is shipped from the factory.Alternatively, the UID may be written elsewhere on the disc. As long asthe UID is written to a fixed location after disc initialization, theUID may be recorded to that location beforehand.

[0282] The next-generation MD1 system utilizes the same disc as that ofthe current MD system. That means a huge number of current MD systemdiscs already marketed with no UID recorded on any of them are to beused by the next-generation MD1 system.

[0283] New standards have thus been established to allocate aspecifically protected area on each of these numerous current MD systemdiscs that may be utilized by the next-generation MD1 system. Uponinitialization of any of these discs, the disc drive unit 1 writes arandom number signal to the protected area for use as the UID of thedisc in question. Under new standards, users are prohibited fromaccessing the UID-filled area. The UID is not limited to random numbersignals; it may be given as the combination of a manufacturer code, anequipment code, an equipment serial number, and a random number. It isalso possible to combine at least one of the manufacturer code,equipment code, and equipment serial number, with a random number foruse as the UID.

[0284]FIG. 18 is a flowchart of steps for initializing a next-generationMD1 disc. In the first step S100 of FIG. 18, a predetermined location onthe disc is accessed to determine whether a UID is recorded there. If aUID is judged as being recorded, the UID is read and placed temporarilyinto, say, the auxiliary memory 5.

[0285] The location to be accessed in step S100 is an area outside theFAT area in the next-generation MD1 system format, such as the lead-inarea. If the disc 90 in question was initialized in the past and isalready furnished with a DDT area, that area may be accessed instead.Step S100 may be skipped where appropriate.

[0286] In step S101, data are recorded to the U-TOC area in an EFMmodulation process. Written at this point to the U-TOC is informationfor securing two kinds of areas: an alert track, and an area of tracksfollowing the DDT area, i.e., an area in which data are to be recordedin 1-7 pp modulation format. In step S102, data are written to the alerttrack in EFM format. In step S103, data are written to the DDT area in1-7 pp modulation format.

[0287] In step S104, a UID is recorded outside the FAT area such as inthe DDT area. If the UID was read from its predetermined location andplaced into the auxiliary memory 5 in step S100 above, that UID isrecorded here. If in step S100 the UID was not judged as being writtenin a predetermined location on the disc or if step S100 is skippedoutright, a UID is generated based on a random number signal and thegenerated UID is recorded. The UID is generated illustratively by thesystem controller 9. The generated UID is fed to the media drive unit 2via the memory transfer controller 3 before being written to the disc90.

[0288] In step S105, FAT and other data are written to the area for datastorage in 1-7 pp modulation format. In other words, the UID is recordedoutside the FAT area. For the next-generation MD1 system, as describedabove, initialization of the recordable area managed under the FATscheme is not mandatory.

[0289]FIG. 19 is a flowchart of steps for initializing a next-generationMD2 disc. In the first step S110 of FIG. 19, a predetermined locationwhere a UID is supposed to be recorded beforehand such as the lead-inarea, or the DDT area if the disc was initialized in the past, isaccessed to determine whether a UID is recorded there. If the UID isjudged recorded, that UID is read and plated temporarily in, say, theauxiliary memory 5. Because the UID recording location is fixedlydetermined in the format, it can be accessed directly without referenceto any other management information on the disc. This feature may alsobe applied to the processing discussed above with reference to FIG. 18.

[0290] In step S11l, data are recorded to the DDT area in 1-7 ppmodulation format. In step S112, the UID is recorded outside the FATarea such as in the DDT area. The UID recorded at this point is the UIDthat was retrieved from the predetermined location on the disc andplaced into the auxiliary memory 5 in step S110. If in step S110 the UIDwas not judged recorded in the predetermined location on the disc, thena UID is generated on the basis of a random number signal, and thegenerated UID is written. The UID is generated illustratively by thesystem controller 9. The generated UID is fed to the media drive unit 2via the memory transfer controller 3 before being written to the disc90.

[0291] In step S113, FAT and other data are recorded. The UID isrecorded outside the FAT area. For the next-generation MD2 system, asdescribed above, initialization of the recordable area managed under theFAT scheme is not effected.

[0292] 6. First Example of the Audio Data Management System

[0293] As discussed above, the next-generation MD1 and MD2 systemsembodying this invention have their data managed by the FAT system.Audio data to be recorded are compressed by a predetermined datacompression method and encrypted for copyright protection. The audiodata compression method is illustratively ATRAC3 or ATRAC5. It is alsopossible to adopt MP3 (MPEG1 Audio Layer 3), AAC (MPEG2 Advanced AudioCoding), or other suitable compression method. Not only audio data butalso still image data and moving image data may be handled. Since theFAT system is in use, general-purpose data may also be recorded andreproduced by the next-generation MD1 and MD2 systems. Furthermore,computer-readable and executable instructions may be encoded on the discso the MD1 or MD2 may also contain executable files.

[0294] Described below is a system for managing audio data as they arerecorded and reproduced to and from the next-generation MD1 and MD2discs.

[0295] Because the next-generation MD1 and MD2 systems are designed toreproduce high-quality audio data for extended periods of time, thereare a large number of audio data items to be managed on a single disc.Since the FAT system is adopted for data management purposes, bettercompatibility with computers is ensured. This feature, however, asrecognized by the present inventors, has its advantages anddisadvantages. Whereas the ease of operation is enhanced on the part ofusers, audio data could be copied illegally to the detriment ofcopyright holders. These characteristics were especially taken intoconsideration in the development of the inventive audio data managementsystem.

[0296]FIG. 28 is an explanatory view of a first example of the audiodata management system. As shown in FIG. 28, the audio data managementsystem in its first-example setup generates a track index file and anaudio data file on the disc. These are the files managed by the FATsystem.

[0297] The audio data file is a file that accommodates a plurality ofaudio data items as illustrated in FIG. 29. When viewed from the FATsystem, the audio data file appears to be a very large file. The insideof this file is divided into parts, so that audio data are handled as aset of such parts.

[0298] The track index file is a file that describes various types ofinformation for managing the audio data contained in the audio datafile. As shown in FIG. 30, the track index file is made up of a playorder table, a programmed play order table, a group information table, atrack information table, a part information table, and a name table.

[0299] The play order table indicates the order of audio datareproduction defined by default. As shown in FIG. 31, the play ordertable contains information items TINF1, TINF2, etc., representing linksto track descriptors (FIG. 34A) corresponding to track numbers (i.e.,music title numbers) in the track information table. Track numbers areillustratively serial numbers starting from “1.”

[0300] The programmed play order table contains the order of audio datareproduction defined by the individual user. As shown in FIG. 32, theprogrammed play order table describes programmed track information itemsPINF1, PINF2, etc., representing links to the track descriptorscorresponding to the track numbers.

[0301] The group information table, as depicted in FIGS. 33A and 33B,describes information about groups. A group is defined as a set of oneor more tracks having serial track numbers, or a set of one or moretracks with programmed serial track numbers. Specifically, the groupinformation table is made of group descriptors representing track groupsas shown in FIG. 33A. Each group descriptor describes a start tracknumber, an end track number, a group name, and a flag regarding thegroup in question as indicated in FIG. 33B.

[0302] The track information table describes information about tracks,i.e., music titles as shown in FIGS. 34A and 34B. Specifically, thetrack information table is made up of track descriptors representingtracks (music titles) as indicated in FIG. 34A. Each track descriptor,as depicted in FIG. 34B, contains a coding system, copyright managementinformation, content decryption key information, pointer informationpointing to the part number serving as the entry to the music title ofthe track in question, an artist name, a title name, original titleorder information, and recording time information about the track inquestion. The artist name and title name do not contain actual names butdescribe pointer information pointing to relevant entries in the nametable. The coding system represents a codec operating scheme serving asdecryption information.

[0303] The part information table describes pointers allowing partnumbers to point to actual music title locations as shown in FIGS. 35Aand 35B. Specifically, the part information table is made up of partdescriptors corresponding to parts as depicted in FIG. 35A. A part isrepresentative of one track in its entirety or one of multiple partsconstituting a single track. FIG. 35B indicates entries of a partdescriptor in the part information table. As shown in FIG. 35B, eachpart descriptor is composed of a start address and an end address of thepart in question in the audio data file, and a link to the next part.

[0304] The addresses used as part number pointer information, name tablepointer information, and audio file location pointer information mayeach be given in the form of a file byte offset, a part descriptornumber, a FAT cluster number, or a physical address of a disc utilizedas a storage medium. The file byte offset is a specific implementationof an offset scheme that may be implemented according to the presentinvention, where the part pointer information is an offset value inpredetermined units (e.g., bytes, bits, and n-bit blocks) from abeginning of the audio file.

[0305] The name table is a table of text making up actual names. Asshown in FIG. 36A, the name table is made of a plurality of name slots.Each name slot is linked with and called by a pointer pointing to thename in question. A pointer for calling up a name may be an artist nameor a title name in the track information table, or a group name in thegroup information table. One name slot may be called from a plurality ofpointers. As depicted in FIG. 36B, each name slot is composed of namedata constituting text information, a name type serving as an attributeof the text information, and a link to another name slot. A name toolong to be accommodated in a single name slot may be divided into aplurality of name slots. The divided name slots are traced one afteranother using links describing the whole name.

[0306] The first example of the audio data management system accordingto the invention works as follow: as illustrated in FIG. 37, the tracknumber of a target track to be reproduced is first designated in theplay order table (FIG. 31). With the track number designated, access isgained through a link to the track descriptor (FIGS. 34A and 34B) in thetrack information table, and the linked track descriptor is retrievedfrom the table. Read from the track descriptor are: a coding system,copyright management information, content decryption key information,pointer information pointing to the part number serving as the entry tothe music title of the track in question, an artist name pointer, atitle name pointer, original title order information, and recording timeinformation about the track in question.

[0307] Based on the part number information read from the trackinformation table, access is gained through a link to the applicablepart descriptor in the part information table (FIGS. 35A and 35B). Fromthe part information table, the audio data file is accessed at the partcorresponding to the start address of the track (title) in question.When access is gained to the data at the part whose location in theaudio data file is designated by the part information table,reproduction of audio data is started from that location. At this time,the reproduced data are decrypted in accordance with the coding systemread from the applicable track descriptor in the track informationtable. If the audio data are encrypted, the key information read fromthe track descriptor is used to decrypt the data.

[0308] If there is any part following the part in question, a link tothe destination part is described in the part descriptor. The relevantpart descriptors are read one after another in accordance with thelinks, so that the audio data in the audio data file are reproduced fromthe parts whose locations are designated by the accessed partdescriptors. These steps allow the audio data to be reproduced from thedesired track (music title).

[0309] A name slot (FIG. 36A) in the name table is called from thelocation (or name pointer information) designated by an artist namepointer or a title name pointer read from the track information table.Name data are read from the name slot thus called. The name pointerinformation may be a name slot number, a cluster number in a fileallocation table system, or a physical address of a storage medium, forexample.

[0310] Each name slot in the name table may be referenced from aplurality of pointers as mentioned above. For example, where multipletitles of the same artist are recorded, the same name slot in the nametable is referenced from a plurality of pointers in the trackinformation table as shown in FIG. 38. In the example of FIG. 38, trackdescriptors “1,” “2,” and “4” represent the music titles all belongingto the same artist “DEF BAND,” so that the same name slot is referencedfrom each of these track descriptors. Also in FIG. 38, track descriptors“3,” “5,” and “6” represent the music titles all belonging to the sameartist “GHQ GIRLS,” so that the same name slot is also referenced fromeach of these track descriptors. When each name slot in the name tableis allowed to be referenced from a plurality of pointers, the size ofthe name table can be reduced appreciably.

[0311] Furthermore, information about a given artist name may bedisplayed by use of links to the name table. If it is desired to displaya list of music titles belonging to, say, the artist named “DEF BAND,”the track descriptors referencing the same name slot “DEF BAND” aretraced and their information is displayed. In this example, the trackdescriptors “1,” “2,” and “4” referencing the address in the name slot“DEF BAND” are traced and the descriptor information is acquired. Theinformation thus obtained permits a display of the music titles whichbelong to the artist named “DEF BAND” and which are held on this disc.There are no links going from the name table back to the trackinformation table, because each name slot in the name table is allowedto be referenced from a plurality of pointers.

[0312] When audio data are to be recorded anew, an unused area made upof at least a predetermined number of consecutive recording blocks(e.g., four recording blocks) is allocated according to the FAT table.Recording blocks are allocated consecutively so as to minimize wastagein accessing the recorded audio data.

[0313] When the audio data recordable area is allocated, a new trackdescriptor is assigned to the track information table, and a content keyfor encrypting the audio data in question is generated. The input audiodata are encrypted using the key before getting recorded to the unusedarea allocated. The area in which the audio data have been recorded ischained to the tail end of the audio data file in the FAT file system.

[0314] With the new audio data chained to the audio data file,information about the chained location is generated, and the newlygenerated audio data location information is written to a newly assignedpart descriptor. Key information and a part number are written to thenew track descriptor. If necessary, an artist name and a title name arewritten to relevant name slots. In the track descriptor, pointers aredescribed with links to the artist name and title name. The number ofthe track descriptor in question is written to the play order table, andthe applicable copyright management information is updated.

[0315] When audio data are to be reproduced from a particular track,information about the designated track number is retrieved from the playorder table. The track descriptor corresponding to the track from whichto reproduce the audio data is then acquired.

[0316] Key information is obtained from the applicable track descriptorin the track information table, and the part descriptor indicating thearea containing entry data is acquired. From the part descriptor, accessis gained to the location, in the audio data file, of the first partcontaining the desired audio data, and data are retrieved from theaccessed location. The reproduced data from the location are decryptedusing the acquired key information for audio data reproduction. If thepart descriptor has a link to another part, the linked part is accessedand the above steps are repeated.

[0317] Suppose that it is desired to change a track number “n” of agiven track in the play order table into a track number “n+m.” In thatcase, a track descriptor Dn describing information about the track inquestion is first obtained from a track information item TINFn in theplay order table. All values representing track information itemsTINFn+1 through TINFn+m (i.e., track descriptor numbers) are advanced byone place. The number of the track descriptor Dn is then written to thetrack information item TINFn+m.

[0318] Suppose now that a track with a track number “n” is desired to beerased. In this case, the track descriptor Dn describing the informationabout the track is acquired from the track information item TINFn in theplay order table. All valid track descriptor numbers following the trackinformation entry TINFn+1 in the play order table are advanced by oneplace. Moreover, because the track “n” is to be erased, all trackinformation entries that follow track “n” are advanced in the play orderby one place. Based on the track descriptor Dn thus obtained for thetrack to be deleted, the coding system and the decryption keycorresponding to the track in question are acquired from the trackinformation table. Also acquired is the number of a part descriptor Pnindicating the area containing the start audio data. An audio block withits range designated by the part descriptor Pn is detached from theaudio data file in the FAT file system. Then the track descriptor Dn ofthe track in question is erased from the track information table and thepart descriptor is erased from the part information table so as to freethe part description on the file system.

[0319] Suppose that in FIG. 39A, parts A, B, and C have been chained andthat part B is desired to be erased. It is assumed here that the parts Aand B share the same audio block (and the same FAT cluster) and that theFAT chain is continuous. It is also assumed that while the part C islocated immediately after the part B in the audio data file, the parts Cand B are in fact found positioned apart when the FAT table is checked.

[0320] In that case, as shown in FIG. 39B, erasing the part B allows twoFAT clusters not sharing any cluster with that part to be detached fromthe FAT chain (i.e., reverted to free areas). In other words, the audiodata file is shortened by four audio blocks. As a result, a number “4”is subtracted from each of the numbers of the audio blocks recorded inthe part C and subsequent parts.

[0321] Part of a track may be erased instead of the track as a whole. Ifa track is partially erased, information about the remaining track maybe decrypted using the coding system and the decryption key whichcorrespond to the track in question and which are acquired from therelevant part descriptor Pn in the track information table.

[0322] If it is desired to combine a track “n” with a track “n+l” in theplay order table, a track descriptor number Dn is acquired from a trackinformation item TINFn in the play order table, the track descriptordescribing information about the track “n”; and a track descriptornumber Dm is obtained from a track information item TINFn+1 in the playorder table, the track descriptor describing information about the track“n+1.” All valid TINF values (track descriptor numbers) following theitem TINFn+1 in the play order table are advanced by one place. A searchis made through the programmed play order table in order to erase alltracks referencing the track descriptor Dm. A new encryption key isgenerated, and a part descriptor list is obtained from the trackdescriptor Dn. To the tail end of that part descriptor list, anotherpart descriptor list extracted from the track descriptor Dm is attached.

[0323] Where two tracks are to be combined, their track descriptors needto be compared so as to ascertain that the copyrights involved are notcompromised. Part descriptors need to be obtained from these trackdescriptors to make sure, with reference to the FAT table, thatfragmentation-related requirements are met upon combination of the twotracks. It may also be necessary to update pointers to the name table.

[0324] Where the track “n” is desired to be divided into a track “n” anda track “n+1,” the track descriptor number Dn describing informationabout the track “In” is first acquired from the track information itemTINFn in the play order table. From the track information item TINFn+1in the play order table, the track descriptor number Dm describinginformation about the track “n+1” is obtained. All valid TINF values(track descriptor numbers) following the track information item TINFn+1in the play order table are advanced by one place. A new key isgenerated for the track descriptor Dn. The part descriptor list isextracted from the track descriptor Dn. A new part descriptor isallocated, and the part descriptor content in effect before the trackdivision is copied to the newly allocated part descriptor. The partdescriptor containing a dividing point is shortened up to that point,and any part descriptor links subsequent to the dividing point arediscarded. The newly allocated part descriptor is set immediately afterthe dividing point.

[0325] 7. Second Example of the Audio Data Management System

[0326] A second example of the audio data management system according tothe invention will now be described. FIG. 40 is an explanatory view of asecond-example setup of the inventive audio data management system. Asshown in FIG. 40, the audio data management system of this exampleinvolves generating a track index file and a plurality of audio datafiles on the disc. These files are managed by the FAT system.

[0327] Each audio data file, as shown in FIG. 41, accommodates audiodata constituting a single music title (piece of music) in principle.The audio data file has a header that includes a title, decryption keyinformation, copyright management information, and index information.Indexes are used to divide one piece of music on a single track into aplurality of tracks. The header records the locations of index-dividedtracks in conjunction with index numbers. Illustratively, up to 255indexes may be set to a track.

[0328] The track index file is a file that describes various items ofinformation for managing the audio data retained in audio data files. Asshown in FIG. 42, the track index file is made up of a play order table,a programmed play order table, a group information table, a trackinformation table, and a name table.

[0329] The play order table indicates the order of audio datareproduction defined by default. As shown in FIG. 43, the play ordertable contains information items TINF1, TINF2, etc., representing linksto track descriptors (FIG. 46A) corresponding to track numbers (i.e.,music title numbers) in the track information table. Track numbers areillustratively serial numbers starting from “1.”

[0330] The programmed play order table contains the order of audio datareproduction defined by the individual user. As shown in FIG. 44, theprogrammed play order table describes programmed track information itemsPINF1, PINF2, etc., representing links to the track descriptorscorresponding to the track numbers.

[0331] The group information table, as depicted in FIGS. 45A and 45B,describes information about groups. A group is defined as a set of oneor more tracks having serial track numbers, or a set of one or moretracks with programmed serial track numbers. Specifically, the groupinformation table is made of group descriptors representing track groupsas shown in FIG. 45A. Each group descriptor describes a start tracknumber, an end track number, a group name, and a flag regarding thegroup in question as indicated in FIG. 45B.

[0332] The track information table describes information about tracks,i.e., music titles as shown in FIGS. 46A and 46B. Specifically, thetrack information table is made up of track descriptors representingtracks (music titles) as indicated in FIG. 46A. Each track descriptor,as depicted in FIG. 46B, includes a file pointer pointing to the audiodata file of the track in question, an index number of the track, anartist name, a title name, original title order information, andrecording time information about the track. The artist name and titlename do not contain actual names but describe pointer informationpointing to relevant entries in the name table.

[0333] The name table is a table of texts making up actual names. Asshown in FIG. 47A, the name table is made of a plurality of name slots.Each name slot is linked with and called by a pointer pointing to thename in question. A pointer for calling up a name may be an artist nameor a title name in the track information table, or a group name in thegroup information table. One name slot may be called from a plurality ofpointers. As depicted in FIG. 47B, each name slot is composed of namedata, a name type, and a link to another name slot. A name too long tobe accommodated in a single name slot may be divided into a plurality ofname slots. The divided name slots are traced one after another usinglinks describing the whole name.

[0334] The second example of the audio data management system accordingto the invention works as follow: as illustrated in FIG. 48, the tracknumber of a target track to be reproduced is first designated in theplay order table (FIG. 43). With the track number designated, access isgained through a link to the track descriptor (FIGS. 46A and 46B) in thetrack information table, and the linked track descriptor is retrievedfrom the table. Read from the track descriptor are: a file pointerpointing to the audio data file in question, an index number of thetrack in question, an artist name pointer, a title name pointer,original title order information, and recording time information aboutthe track.

[0335] Based on the audio data file pointer, the audio data file inquestion is accessed and information is read from the header of thefile. If the audio data are encrypted, the key information read from theheader is used to decrypt the data for audio data reproduction. If anindex number is designated, the location of the designated index numberis detected from the header information, and audio data reproduction isstarted from the location of that index number.

[0336] A name slot is called from the location designated by the artistname pointer or the title name pointer retrieved from the trackinformation table. Name data are read from the name slot thus called.

[0337] When audio data are to be recorded anew, an unused area made upof at least a predetermined number of consecutive recording blocks(e.g., four recording blocks) is allocated according to the FAT table.

[0338] When the audio data recordable area is allocated, a new trackdescriptor is assigned to the track information table, and a content keyfor encrypting the audio data in question is generated. The input audiodata are encrypted using the key, and an audio data file is generatedwith the encrypted audio data.

[0339] A file pointer of the newly generated audio data file and keyinformation are written to the newly assigned track descriptor. Ifnecessary, an artist name and a title name are written to relevant nameslots. In the track descriptor, pointers are described with links to theartist name and title name. The number of the track descriptor inquestion is written to the play order table, and the applicablecopyright management information is updated.

[0340] When audio data are to be reproduced from a particular track,information about the designated track number is retrieved from the playorder table. The track descriptor corresponding to the track from whichto reproduce the audio data is then acquired.

[0341] Based on the track descriptor in the track information table, thefile pointer pointing to the audio data file containing the desiredaudio data and the index number of the track in question are obtained.The audio data file is then accessed and key information is acquiredfrom the header of the file. The reproduced data from the audio datafile are decrypted using the acquired key information for audio datareproduction. Where the index number is designated, audio datareproduction is started from the location of the designated indexnumber.

[0342] Where a track “n” is desired to be divided into a track “n” and atrack “n+1,” a track descriptor number Dn describing information aboutthe track “n” is first acquired from a track information item TINFn inthe play order table. From a track information item TINFn+1, a trackdescriptor number Dm describing information about the track “n+1” isobtained. All valid TINF values (track descriptor numbers) following thetrack information item TINFn+1 in the play order table are advanced byone place.

[0343] As shown in FIG. 49, using an index arrangement allows data inone file to be divided into a plurality of indexed areas. The indexnumbers being used and the locations of the indexed areas are written tothe header of the audio track file in question. An audio data filepointer and an index number are written to one track descriptor Dn, andanother audio data file pointer and another index number are written toanother track descriptor Dm. In this case, one piece of music M1 on asingle track in the audio data file is apparently divided into twopieces of music M11 and M12 over two tracks.

[0344] If it is desired to combine a track “n” with a track “n+1” in theplay order table, a track descriptor number Dn describing informationabout the track “n” is acquired from a track information item TINFn inthe play order table, and a track descriptor number Dm describinginformation about the track “n+1” is obtained from a track informationitem TINFn+1 in the play order table.” All valid TINF values (trackdescriptor numbers) following the item TINFn+1 in the play order tableare advanced by one place.

[0345] If the track “n” and track “n+1” are found in the same audio datafile and separated from each other by an index, then erasing the indexinformation from the header of the file allows the tracks to be combinedas illustrated in FIG. 50. Two pieces of music M21 and M22 on the twotracks are thus combined into a single piece of music M23 on one track.

[0346] Suppose that the track “n” is the index-divided latter half of anaudio data file and that the track “n+1” is found at the beginning ofanother audio data file. In that case, as shown in FIG. 51, a header isattached to the data over the index-divided track “n” to create an audiodata file accommodating a piece of music M32. The header is then erasedfrom the audio data file of the track “n+1” carrying another piece ofmusic M41, and the audio data of the track “n+1” with the music titleM41 is connected to the audio data file of the music title M32. The twopieces of music M32 and M41 are thus combined into a single piece ofmusic M51 on one track.

[0347] The processes above are implemented by two functions. Onefunction involves adding a header to each of index-divided tracks,encrypting track data using a different encryption key for each track,and transforming indexed audio data into a single audio data file. Theother function involves erasing header information from a given audiodata file and connecting the data in that file to another audio datafile.

[0348] 8. Operation During Connection with the Personal Computer

[0349] The next-generation MD1 and MD2 systems adopt the FAT system astheir data management system in order to secure compatibility withpersonal computers. It follows that next-generation MD1 and MD2 discsare used to record and reproduce not only audio data but also generaldata handled by personal computers.

[0350] On the disc drive unit 1, audio data are reproduced as they arebeing read from the disc 90. When the ability of the portable-type discdrive unit 1 to access data is taken into account, audio data shouldpreferably be recorded sequentially on the disc. By contrast, thepersonal computer has no consideration for such data continuity whenwriting data to the disc; the PC records data to any free areas foundavailable on the disc.

[0351] The recording/reproducing apparatus of the invention has thepersonal computer 100 connected to the disc drive unit 1 through the USBhub 7 so that the personal computer 100 may write data to the disc 90loaded in the disc drive unit 1. In that setup, general data are writtenunder control of the file system of the personal computer 100, whileaudio data are written under control of the file system of the discdrive unit 1.

[0352]FIGS. 52A and 52B are explanatory views sketching how managementauthority is moved between the personal computer 100 and the disc driveunit 1 connected therewith through the USB hub 7, not shown, dependingon the type of data to be written to the disc loaded in the drive unit1. FIG. 52A shows how general data are transferred from the personalcomputer 100 to the disc drive unit 1 for recording onto the disc 90 inthe drive unit 1. In this case, the file system on the part of thepersonal computer 100 provides FAT management over the disc 900.

[0353] It is assumed that the disc 90 has been formatted by either thenext-generation MD1 system or the next-generation MD2 system.

[0354] Viewed from the personal computer 100, the connected disc driveunit 1 functions apparently as a removable disc under PC control. Thepersonal computer 100 can then write and read data to and from the disc90 in the disc drive unit 1 in the same manner that the PC writes andreads data to and from a flexible disc.

[0355] The file system of the personal computer 100 may be furnished aspart of the capabilities of an OS (Operating System) carried by the PC100. As is well known, the OS may be recorded as suitable program fileson a hard disc drive incorporated in the personal computer 100. Uponstart-up, the program files are read and executed by the personalcomputer 100 to implement the OS capabilities.

[0356]FIG. 52B shows how audio data are transferred from the personalcomputer 100 to the disc drive unit 1 for recording onto the disc 90loaded in the drive unit 1. The audio data are retrieved illustrativelyfrom the hard disc drive (HDD) held by the personal computer 100.

[0357] It is assumed that the personal computer 100 carries utilitysoftware for submitting audio data to ATRAC compression encoding and forrequiring the disc drive unit 1 to write or erase audio data to or fromthe disc 90 loaded in the unit 1. The utility software is also assumedto be capable of referencing a track index file on the disc 90 in thedisc drive unit 1 in order to look up track information recorded on thedisc 90. This utility software is held illustratively as program fileson the HDD of the personal computer 100.

[0358] Described below is how audio data recorded on a storage medium ofthe personal computer 100 are typically transferred and recorded to thedisc 90 loaded in the disc drive unit 1. It is assumed that the utilitysoftware mentioned above is booted in advance.

[0359] The user first performs an operation on the personal computer 100causing it to write desired audio data (called the audio data Ahereunder) from its HDD to the disc 90 loaded in the disc drive unit 1.The operation triggers the utility software to issue a write requestcommand requesting a write operation of the audio data A onto the disc90. The write request command is sent from the personal computer 100 tothe disc drive unit 1.

[0360] The audio data A are then read from the HDD of the personalcomputer 100. The retrieved audio data A are subjected to an ATRACcompression encoding process by the utility software carried by thepersonal computer 100. The process turns the audio data A intoATRAC-compressed data that are transferred from the personal computer100 to the disc drive unit 1.

[0361] Upon receipt of the write request command from the personalcomputer 100, the disc drive unit 1 starts receiving theATRAC-compressed audio data A being transferred from the personalcomputer 100. The disc drive unit 1 recognizes the command as adirective for writing the transferred data to the disc 90 as audio data.

[0362] More specifically, the disc drive unit 1 receives the audio dataA from the personal computer 100 through the USB hub 7. The receiveddata are forwarded to the media drive unit 2 via the USB interface 6 andmemory transfer controller 3. With the audio data A fed to the mediadrive unit 2, the system controller 9 causes the media drive unit 2 towrite the audio data A to the disc 90 under control of the FAT-basedmanagement scheme of the disc drive unit 1. That is, the audio data Aare written to the disc 90 consecutively in increments of four recordingblocks (64 kilobytes×4) based on the FAT system of the disc drive unit1.

[0363] Until the data write operation on the disc 90 is complete, thereoccur exchanges of data, status information, and commands between thepersonal computer 100 and the disc drive unit 1 in keeping with asuitable protocol. The exchanges are performed to control the datatransfer rate in such a manner that neither overflow nor underflow willoccur in the cluster buffer 4.

[0364] In addition to the write request command mentioned above, anerase request command may be utilized by the personal computer 100. Theerase request command is used to request the disc drive unit 1 to eraseaudio data from the disc 90 loaded in the unit 1.

[0365] For example, when the personal computer 100 is connected to thedisc drive unit 1 and the disc 90 is loaded in the unit 1, the utilitysoftware reads the track index file from the disc 90. The retrieved dataare transferred from the disc drive unit 1 to the personal computer 100.Based on the received data, the personal computer 100 may illustrativelydisplay a title list of the audio data held on the disc 90.

[0366] Suppose that the user at the personal computer 100 views thedisplayed title list and performs an operation to erase certain audiodata (called the audio data B hereunder). In that case, informationdesignating the audio data B to be erased is transmitted to the discdrive unit 1 together with an erase request command. Given the eraserequest command, the disc drive unit 1 under its own control erases theaudio data B from the disc 90 as requested.

[0367] Because audio data erasure is executed by the disc drive unit 1under control of its own FAT system, it is possible to erase audio datafrom, say, a huge file combining a plurality of audio data files asexplained above with reference to FIGS. 39A and 39B.

[0368] 9. Restrictions on Copying of Audio Data from the Disc

[0369] Protecting the copyrights of audio data recorded on the disc 90requires establishing appropriate restrictions on their copying to otherstorage media. Consider a case in which audio data held on the disc 90are transferred from the disc drive unit 1 to the personal computer 100for recording illustratively onto the HDD in the PC.

[0370] It is assumed here that the disc 90 has been formatted by eitherthe next-generation MD1 system or the next-generation MD2 system. It isalso assumed that the operations such as check-in and check-out, to bediscussed below, are performed under control of the above-mentionedutility software carried by the personal computer 100.

[0371] Audio data 200 retained on the disc 90 are first moved to thepersonal computer 100 as shown in FIG. 53A. The “move” operationrepresents a series of actions including the copying of the target audiodata 200 to the personal computer 100 and erasure of the audio data inquestion from the original storage medium (i.e., disc 90). That is, themove operation involves deleting the target data from their sourcelocation and moving the data to their new destination.

[0372] A check-out is defined here as the operation of copying data fromone storage medium to another, with a rightful copy count (i.e., thenumber of times source data are allowed to be copied legitimately)decremented by one for the data in question. A check-in is defined asthe operation of erasing checked-out data from the checkout destination,with the rightful copy count for the checked-out original dataincremented by one.

[0373] When the audio data 200 are moved to the personal computer 100,the data are sent (as audio data 200′) to the storage medium such as theHDD of the personal computer 100 for recording thereto, and the audiodata 200 are erased from the disc 90. The personal computer 100 thensets an allowable (or some predetermined) checkout (CO) count 201 forthe moved audio data 200′ as shown in FIG. 53B. In this example, theallowable check-out count is set for “3” as indicated by three filled-incircles in the figure. The audio data 200′ are allowed to be checked outfrom the personal computer 100 to an external storage medium as manytimes as the allowable check-out count thus established.

[0374] If the checked-out audio data 200 remained erased from theoriginal disc 90, it would be inconvenient for the user. The possibleinconvenience is redressed when the audio data 200′ checked out to thepersonal computer 100 are written back to the disc 90.

[0375] When the audio data 200′ are written back to the original disc 90from the personal computer 100, the allowable check-out count isdecremented by one (3−1=2) as shown in FIG. 53C. At this point, theaudio data 200′ held in the personal computer 100 can still be checkedout rightfully twice and thus will not be erased from the PC 100. As aresult, the audio data 200′ are copied from the personal computer 100 tothe disc 90 and held there as audio data 200″.

[0376] The allowable check-out count 201 is managed by use of thecopyright management information contained in the track descriptors inthe track information table (see FIG. 34B). Because each track isassigned its own track descriptor, the allowable check-out count can beset for each track (each piece of audio data). A track descriptor copiedfrom the disc 90 to the personal computer 100 is used as controlinformation for managing the corresponding audio data moved into the PC100.

[0377] Illustratively, when any audio data are moved from the disc 90 tothe personal computer 100, the track descriptor corresponding to themoved audio data is copied to the PC 100. The personal computer 100utilizes the copied track descriptor in managing the audio data movedfrom the disc 90. When the moved audio data are recorded to, say, theHDD of the personal computer 100, a predetermined allowable check-outcount 201 (“3” in this example) is set to the copyright managementinformation in the track descriptor.

[0378] In addition to the allowable check-out count, the copyrightmanagement information includes an equipment ID for identifying thecheck-out source device and a content ID for identifying the checked-outcontent (i.e., audio data). In the setup of FIG. 53C, the equipment IDof the copy destination device is verified based on the equipment ID inthe copyright management information corresponding to the audio data tobe copied. If the equipment ID in the copyright management informationdoes not match the equipment ID of the copy destination device, copyingis not permitted.

[0379] In the check-out processes of FIGS. 53A through 53C, the audiodata held on the disc 90 are moved to the personal computer 100 and thenwritten back to the disc 90. The procedure appears complicated from theuser's viewpoint and could be perceived as a waste of time because ofthe times involved in reading the audio data from the disc 90 andwriting the same data back to the disc 90. Furthermore, the user wouldfind it aberrant for the audio data to be erased, even temporarily, fromthe disc 90.

[0380] Such awkwardness is avoided by skipping some of the above stepsupon a check-out of audio data from the disc 90, so that the outcome inFIG. 53C is reached in more simplified fashion. Explained below is onesuch simplified procedure executed in response to a single command fromthe user, such as “Check out audio data named XX from the disc 90.”

[0381] (1) The target audio data are copied from the disc 90 to the HDDof the personal computer 100, and the audio data recorded on the disc 90are erased by disabling part of the management data about the audio datain question. For example, a link information item TINFn linked to thetrack descriptor corresponding to the audio data is erased from the playorder table, and a link information item PINFn linked to the trackdescriptor corresponding to the audio data is deleted from theprogrammed file order table. Alternatively, the track descriptorsthemselves corresponding to the audio data in question may be erased.This step renders the audio data unusable of the disc 90, after movingthe data from the disc 90 to the personal computer 100.

[0382] (2) When the audio data are copied to the personal computer 100in step (1) above, the track descriptors corresponding to the audio dataare also copied to the HDD of the PC 100.

[0383] (3) The personal computer 100 records a predetermined allowablecheck-out count (e.g., three times) to the copyright managementinformation in the track descriptors corresponding to the audio datacopied (i.e., moved) from the disc 90.

[0384] (4) Based on the track descriptors copied from the disc 90, thepersonal computer 100 acquires a content ID corresponding to the movedaudio data. This content ID is recorded as indicative of the audio datathat may be checked in subsequently.

[0385] (5) The personal computer 100 then decrements by one theallowable check-out count recorded in step (3) above to the copyrightmanagement information in the track descriptors corresponding to themoved audio data. In this example, the allowable check-out count is nowreduced to “2” (=3−1)

[0386] (6) On the disc drive unit 1, not shown, in which the disc 90 isloaded, the track descriptors corresponding to the moved audio data areenabled. This is accomplished illustratively by restoring orreconstituting the link information items TINFn and PINFn erased in step(1) above. Where the track descriptors themselves corresponding to theaudio data were erased earlier, these track descriptors arereconstituted. Alternatively, the corresponding track descriptors may betransferred from the personal computer 100 to the disc drive unit 1 forrecording onto the disc 90.

[0387] Carrying out steps (1) through (6) above completes the entirecheck-out procedure. The steps permit copying of desired audio data fromthe disc 90 to the personal computer 100 while sparing the userredundant chores and ensuring copyright protection for the audio data inquestion.

[0388] The audio data copying steps (1) through (6) above are appliedpreferably to the audio data that were recorded onto the disc 90 by theuser operating the disc drive unit 1.

[0389] Checked-out audio data are checked in as follows: the personalcomputer 100 first searches for the desired data from among the audiodata recorded therein, as well as for control information such ascopyright management information in the corresponding track descriptors.With the audio data and the control information found and ascertained,the target data are checked in accordingly.

[0390] 10. Coexistence of the Next-Generation MD1 System with theCurrent MD System

[0391] The next-generation MD1 system can use the same disc adopted bythe current MD system, even thought the disc format of thenext-generation MD1 system differs significantly from the disc format ofthe current MD system. This necessitates making arrangements that willkeep the user from getting confused when using either of the two discformats on the same disc drive unit 1.

[0392]FIG. 54 is a schematic view portraying conceptually how thenext-generation MD1 system and the current MD system may coexist in thedisc drive unit 1. The disc drive unit 1 complies with both digital andanalog formats for the audio signal to be input and output.

[0393] Given a digital audio signal, a next-generation MD1 system 70 inFIG. 54 detects a watermark from the signal by a predetermined method,gets an encryption unit 72 to encrypt the signal using key information74, and feeds the encrypted signal to a recording/reproduction unit 73.If an analog audio signal is supplied, the MD1 system 70 gets an A/Dconverter, not shown, to covert the signal into a digital audio datasignal, detects a watermark from the audio data signal, encrypts thesignal, and sends the encrypted signal to the recording/reproductionunit 73. The recording/reproduction unit 73 subjects the encrypted audiodata to ATRAC compression encoding. The compression-coded audio data areconverted to 1-7 pp modulation format together with the key information74 before getting recorded to the disc 90, not shown.

[0394] If the watermark detected from the input audio signal containsillustratively copy guard information, then the recording/reproductionunit 73 may be inhibited from carrying out any write operationaccordingly.

[0395] For audio data reproduction, both the audio data and thecorresponding key information 74 are read from the disc 90 by therecording/reproduction unit 73. The data are decrypted by a decryptionunit 75 using the key information 74, whereby a digital audio signal isacquired. The digital audio signal thus obtained is converted to ananalog audio signal by a D/A converter, not shown, for output.Alternatively, the digital audio signal may be output unconvertedwithout the intervention of the D/A converter. A watermark may also bedetected from the audio signal being reproduced from the disc 90.

[0396] If the detected watermark is judged to include copy guardinformation, the recording/reproduction unit 73 may be inhibited fromcarrying out audio data reproduction accordingly.

[0397] In a current MD system 71 of FIG. 54, a digital audio signal isfurnished with generation management information by SCMS (Serial CopyManagement System) before being forwarded to a recording/reproductionunit 76. An analog audio signal, if supplied, is converted to digitalaudio data by an A/D converter, not shown, before being fed to therecording/reproduction unit 76. The analog audio signal is not furnishedwith generation management information by SCMS. Therecording/reproduction unit 76 submits the received audio data to ATRACcompression encoding. The compression-coded audio data are converted toEFM format before being written to the disc 90, not shown.

[0398] For audio data reproduction, the desired audio data are read as adigital audio signal from the disc 90 by the recording/reproduction unit76. The digital audio signal is converted to an analog audio signal bythe D/A converter, not shown, for output. Alternatively, the digitalaudio signal may be output unconverted without the intervention of theD/A converter.

[0399] In the above-described disc drive unit 1 in which thenext-generation MD1 system and the current MD system coexist, a switch50 is provided to switch explicitly between the operation modes of thetwo MD systems. In particular, the switch 50 is used effectively whenaudio data are to be recorded to the disc 90.

[0400]FIG. 55 is an external view of a portable-type disc drive unit 1.The disc drive unit 1 is equipped with a hinge, which is located in therear and hidden in FIG. 55. Sliding on a slider 52 allows a lid 54around the hinge to swing open away from a body 55. A disc guide appearsin the opening through which to insert the disc 90. When the disc 90 isinserted along the guide and the lid 54 is swung shut, the disc 90 isloaded into the disc drive unit 1. With the disc 90 thus loaded, thedisc drive unit 1 automatically reads information from the lead-in areaand U-TOC area of the disc 90.

[0401] A phone jack 53 serves as an analog audio signal output terminal.The user may plug audio reproduction means such as headphones into thephone jack 53 to enjoy the sound of audio data reproduced from the disc90.

[0402] Although not shown in FIG. 55, the disc drive unit 1 is alsoprovided with various keys for control purposes: keys for designatingdisc operations such as play, record, stop, pause, fast forward, andrewind; keys for editing the audio data and other information held onthe disc 90; and keys for inputting commands and data into the discdrive unit 1. These keys are located illustratively on the body 55.

[0403] The above-mentioned switch 50 is attached illustratively to thelid 54 of the disc drive unit 1. As shown in FIG. 55, the switch 50 ismade fairly large in size and located conspicuously to attract theuser's attention. On the disc drive unit 1 in FIG. 55, the switch 50 isshown switchable either to “MD” for the operation mode of the current MDsystem or to “NEXT-GENERATION MD” for the operation mode of thenext-generation MD1 system.

[0404] The lid 54 is also equipped with a display unit 51. The displayunit 51 displays various operation states of the disc drive unit 1 andtrack information from the disc 90 loaded in the unit 1. The displayunit 51 also gives onscreen indications in conjunction with theoperation mode set by use of the switch 50.

[0405] Described below with reference to the flowchart of FIG. 56 is howthe disc drive unit 1 typically works when formatting the disc 90. Thesteps in FIG. 56 apply when a so-called virgin disc (unused disc) is tobe formatted. In the first step S200 of FIG. 56, a current MD systemdisc 90 is loaded into the disc drive unit 1. With the disc 90 loaded,step S201 is reached in which information is read first from the lead-inarea and then from the U-TOC area on the disc 90.

[0406] In step S202, a check is made to see whether the operation modeof the disc drive unit 1 is set by the switch 50 for the current MDsystem or for the next-generation MD1 system. If in step S202 theoperation mode is judged set for the current MD system, step S203 isreached. In step S203, the loaded disc 90 is judged usable as a currentMD system disc with no need for further formatting, which ischaracteristic of the current MD system. The display unit 51 then givesan onscreen indication saying that the disc 90 is a blank disc.

[0407] If in step S202 the operation mode of the disc drive unit 1 isjudged set for the next-generation MD1 system, then step S204 isreached. In step S204, the display unit 51 indicates that the disc 90 isa blank disc for a period of, say, several seconds before step S205 isreached automatically.

[0408] In step S205, the display unit 51 is made to display a messageasking the user whether or not to proceed with formatting of the disc90. If the user gives an instruction specifying that the disc 90 is tobe formatted, step S206 is reached. Illustratively, the instruction isentered into the disc drive unit 1 by the user operating a suitable keyon the body 55 of the unit 1.

[0409] In step S206, the disc drive unit 1 submits the disc 90 to aformatting process of the next-generation MD1 system in the mannerdescribed earlier with reference to the flowchart of FIG. 18. While thedisc 90 is being formatted, the display unit 51 should preferablyindicate the formatting process is in progress. With the formattingprocess completed in step S206, step S207 is reached. In step S207, thedisplay unit 51 is made to give a message saying that the loaded disc 90is a blank next-generation MD1 disc.

[0410] If in step S205 the user gives an instruction that the disc 90 isnot to be formatted, step S205 is followed by step S208. In step S208,the display unit 51 gives an indication prompting the user to set theswitch 50 for the operation mode of the current MD system in the discdrive unit 1. In step S209, a check is made, upon elapse of apredetermined period of time, to see whether the setting of the switch50 stays unchanged despite the indication on the display unit 51. If thesetting of the switch 50 is judged unchanged in step S209, a time-out isrecognized and control is returned to step S205.

[0411]FIG. 57 is another flowchart of steps carried out by the discdrive unit 1 in formatting a virgin disc 90 loaded therein. In step S300of FIG. 57, a blank (unused) disc 90 is loaded into the disc drive unit1. In step S301, information is read first from the lead-in area andthen from the U-TOC area of the disc 90. In step S302, based on theU-TOC information thus acquired, the display unit 51 is made to give anindication that the loaded disc 90 is a blank disc.

[0412] In step S303, the record key (not shown) on the disc drive unit 1is operated to instruct that data are to be recorded to the disc 90 inthe disc drive unit 1. The recording instruction may be given to thedisc drive unit 1 not only by operation of the record key of the unit 1but also from, say, the personal computer 100 connected to the discdrive unit 1.

[0413] With the recording instruction given to the disc drive unit 1 instep S303, step S304 is reached. In step S304, a check is made to seewhether the operation mode of the disc drive unit 1 is set by the switch50 for the next-generation MD1 system or for the current MD system. Ifin step S304 the operation mode of the disc drive unit 1 is judged setfor the current MD system, then step S306 is reached. In step S306, arecording process of the current MD system is started on the disc 90.

[0414] If in step S304 the operation mode of the disc drive unit 1 isjudged set for the next-generation MD1 system by the switch 50, stepS305 is reached. In step S305, the disc 90 is formatted by thenext-generation MD1 system in the manner described earlier withreference to FIG. 18. Step S305 is followed by step S306 in which arecording process of the next-generation MD1 system is started on theformatted disc 90.

[0415] Described below with reference to the flowchart of FIG. 58 is howthe disc drive unit 1 typically works when recording audio data to thedisc 90. The processing varies depending on whether the operation modeof the disc drive unit 1 matches the type of the disc 90, i.e., whetherthe disc 90 has been formatted by the next-generation MD1 system.

[0416] In the first step S210 of FIG. 58, the disc 90 is loaded into thedisc drive unit 1. With the disc 90 loaded, step S211 is reached inwhich information is read first from the lead-in area and then from theU-TOC area of the disc 90.

[0417] Based on the U-TOC information thus retrieved, a check is made instep S212 to determine whether the loaded disc 90 has the format of thenext-generation MD1 system or the format of the current MD system. Thecheck is made illustratively on the basis of whether FAT data have beenretrieved from the U-TOC area. Alternatively, the check may be carriedout based on whether alert track start location information is found inthe U-TOC area.

[0418] In step S213, the display unit 51 is made to indicate the disctype determined in step S212. In step S214, the status of the loadeddisc 90 is displayed on the display unit 51 in accordance with theinformation read from the U-TOC area. Illustratively, the displayindicates whether the loaded disc 90 is a blank disc. If the disc 90 isnot a blank disc, the disc name and track name information aredisplayed. In step S215, the rotation of the disc 90 is stopped.

[0419] In step S216, a check is made to see if the disc type determinedin step S212 matches the operation mode of the disc drive unit 1 set bythe switch 50. In case of a match, step S217 is reached.

[0420] More specifically, step S217 is reached in one of two cases:where the switch 50 is judged set for the operation mode of the currentMD system and the loaded disc 90 turns out to be a current MD systemdisc on the one hand; and where the switch 50 is judged set for theoperation mode of the next-generation MD1 system and the loaded disc 90is found to have the format of the next-generation MD1 system on theother hand.

[0421] In step S217, data may be recorded to or reproduced from the disc90. It is also possible to edit information in the U-TOC area on thedisc 90.

[0422] At this point, depending on the disc type determined in stepS212, the system controller 9 causes the media drive unit 2 to selectusing the selector 26 an appropriate signal path complying with themodulation system for the disc type in effect. This makes it possible toswitch the demodulation formats automatically between thenext-generation MD1 system and the current MD system for audio datareproduction. The file systems are also switched in like manner betweenthe next-generation MD1 system and the current MD system under controlof the system controller 9 based on the disc type in effect.

[0423] It might happen in step S216 that the disc type determined instep S212 does not match the operation mode of the disc drive unit 1 setby the switch 50. In that case, step S216 is followed by step S219.

[0424] More specifically, step S219 is reached in one of two cases:where the switch 50 is judged set for the operation mode of the currentMD system and the loaded disc 90 turns out to have the format of thenext-generation MD1 system on the one hand; and where the switch 50 isjudged set for the operation mode of the next-generation MD1 system andthe loaded disc 90 is found to have the format of the current MD systemon the other hand.

[0425] In step S219, a check is made to see what operation is carriedout by the user on the disc 90. If in step S219 the user is judged tohave performed an operation to reproduce (“PB”) audio data from the disc90, then step S220 is reached. In step S220, the audio data arereproduced from the disc 90 as instructed by the user.

[0426] That is, even if the disc type does not match the operation modeof the disc drive unit 1 set by the switch 50, the audio data recordedon the disc 90 can be reproduced regardless of the setting of the switch50.

[0427] More specifically, depending on the disc type determined in stepS212, the system controller 9 causes the media drive unit 2 to selectusing the selector 26 an appropriate signal path complying with themodulation system for the disc type in effect. This makes it possible toswitch the demodulation formats automatically between thenext-generation MD1 system and the current MD system for audio datareproduction. The file systems are also switched in like manner betweenthe next-generation MD1 system and the current MD system under controlof the system controller 9 based on the disc type in effect.

[0428] If in step S219 the user is judged to have performed an operationto record (“REC”) audio data to the disc 90 or to erase or otherwiseedit (“EDIT”) recorded audio data on the disc 90, then step S218 isreached. In step S218, a warning message appears on the display unit 51saying that the type of the disc 90 does not match the operation mode ofthe disc drive unit 1. Also displayed is a message saying that recordingis not available if the user has designated recording, or that editingis impossible if the user has specified editing.

[0429] If in step S219 the user attempts to update the UTOC area in anediting operation during audio data reproduction, the display unit 51displays two messages: that the type of the disc 90 does not match theoperation mode of the disc drive unit 1, and that editing is notavailable at this stage.

[0430] That is, where the disc type does not comply with the operationmode of the disc drive unit 1 set by the switch 50, no operation, whichwould modify information recorded on the disc 90, is permitted.

[0431] How the disc 90 is changed in its format will now be described.On the disc 90, it is possible to change the format of thenext-generation MD1 system into the format of the current MD system andvice versa.

[0432]FIG. 59 is a flowchart of steps for switching from the disc formatof the next-generation MD1 system to the disc format of the current MDsystem on the disc 90. It is assumed here that the switch 50 is set inadvance for the operation mode of the next-generation MD1 system.

[0433] In the first step S230 of FIG. 59, the disc 90 is loaded into thedisc drive unit 1. With the disc 90 loaded, step S231 is reached inwhich information is read first from the lead-in area and then from theU-TOC area of the disc 90. In step S232, it is recognized that theloaded disc 90 has been formatted by the next-generation MD1 system. Instep S233, the rotation of the disc 90 is stopped.

[0434] In step S234, all data recorded and managed by the FAT system areerased from the disc 90. For example, the user performs an operation toedit data (“EDIT”) recorded under the FAT management scheme on the disc90, and selects from among editing alternatives an operation to eraseall data (“ALL ERASE”). It is preferred in step S234 that an indicationbe given on the display unit 51 asking the user to confirm his or herintention to actually erase all data from the disc 90.

[0435] After all data recorded under the FAT management scheme areerased from the disc 90 according to the user's operation, step S235 isreached. In step S235, a message saying that the loaded disc has nowbecome a blank disc appears on the display unit 51.

[0436] Step S235 is followed by step S236 in which the user operates theswitch 50 to set the operation mode of the disc drive unit 1 for thecurrent MD system. In step S237, information is read from the U-TOC areaof the loaded disc 90. In step S238, the disc 90 is recognized as a discformatted by the next-generation MD1 system.

[0437] In step S239, a message saying that the loaded disc is a blanknext-generation MD1 system disc on the display unit 51. An indicationalso appears on the display unit 51 asking the user whether or not tocancel the format of the next-generation MD1 system. Canceling theformat of the next-generation MD1 system means switching from the discformat of the next-generation MD1 system to the disc format of thecurrent MD system on the loaded disc 90.

[0438] If in step S239 the user is judged to have an operation to cancelthe disc format, step S240 is reached. In step S240, the format of thenext-generation MD1 system on the loaded disc 90 is canceled.Illustratively, the disc format is canceled erasing the FAT informationfrom the T-TOC area as well as the alert track. Alternatively, thenext-generation MD1 system format may be canceled by erasing not the FATinformation but the alert track alone.

[0439] If in step S239 the user is judged to have performed an operationnot to cancel the disc format, step S241 is reached. In step S241, anindication appears on the display unit 51 prompting the user to operatethe switch 50 to set the disc drive unit 1 for the operation mode of thenext-generation MD1 system.

[0440] In step S242, a check is made to see whether the user carries outthe operation to set the disc drive unit 1 for the operation mode of thenext-generation MD1 system within a predetermined period of time. If therelevant operation is judged performed within the predetermined timeperiod, then step S243 is reached in which the processing is terminatedand the loaded disc 90 is rendered usable as a blank disc formatted bythe next-generation MD1 system. If in step S242 the setting of theswitch 50 is not completed within the predetermined time period, atime-out is recognized and control is returned to step S239.

[0441] Switching from the disc format of the current MD system to thedisc format of the next-generation MD1 system is performed as follows:the switch 50 is first operated to set the disc drive unit 1 for theoperation mode of the current MD system. An operation is carried out toerase from the disc 90 all audio data recorded in the format of thecurrent MD system. Then the disc 90 is formatted anew by thenext-generation MD1 system in the manner discussed earlier withreference to FIG. 18.

[0442] With the above features in place, the inventive method andapparatus are capable of managing audio data efficiently under controlof the FAT system using a storage medium whose specifications areequivalent to those of the current MD system.

[0443] While a preferred embodiment of the invention has been describedusing specific terms, such description is for illustrative purposesonly, and it is to be understood that changes and variations may be madewithout departing from the spirit or scope of the following claims.

[0444] The present document contains subject matter related to thatdisclosed in Japanese Patent Application P2002-099277, filed in theJapanese Patent Office (JPO) on Apr. 1, 2002; Japanese PatentApplication P2002-190812, filed in the JPO on Jun. 28, 2002; JapanesePatent Application P2002-099294 filed in the JPO on Apr. 1, 2002;Japanese Patent Application P2002-190811 filed in the JPO on Jun. 28,2002; Japanese Patent Application P2002-099274 filed in the JPO on Apr.1, 2002; Japanese Patent Application P2002-190804 filed in the JPO onJun. 28, 2002; Japanese Patent Application P2002-099278 filed in the JPOon Apr. 1, 2002; Japanese Patent Application P2002-190805 filed Jun. 28,2002; Japanese Patent Application P2002-099276 filed in the JPO on Apr.1, 2002; Japanese Patent Application P2002-190808 filed in the JPO onJun. 28, 2002; Japanese Patent Application P2002-099296 filed in the JPOon Apr. 1, 2002; Japanese Patent Application P2002-190809 filed in theJPO on Jun. 28, 2002; Japanese Patent Application P2002-099272 filed inthe JPO on Apr. 1, 2002; Patent Application P2002-190802 filed in theJPO on Jun. 28, 2002; Japanese Patent Application P2002-099271 filed inthe JPO on Apr. 1, 2002; Japanese Patent Application P2002-190803 filedin the JPO on Jun. 28, 2002; Japanese Patent Application P2002-099270filed in the JPO on Apr. 1, 2002; Japanese Patent ApplicationP2002-190578 filed in the JPO on Jun. 28, 2002; Japanese PatentApplication P2002-099273 filed in the JPO on Apr. 1, 2002; JapanesePatent Application P2002-190810 filed in the JPO on Jun. 28, 2002;Japanese Patent Application P2002-099279 filed in the JPO on Apr. 1,2002; and Japanese Patent Application P2002-190801, filed in the JPO onJun. 28, 2002, the entire contents of each of the above-identifieddocuments being incorporated herein by reference.

What is claimed is:
 1. A track management method comprising the stepsof: obtaining track information from a play order table having aplurality of track information entries arranged in a predetermined playorder, the track information corresponds to a track to be deleted andpoints to a track descriptor in a track information table; obtaining thetrack descriptor from the track information table, said track descriptorincluding a decryption key corresponding to the track to be deleted andpointer information that points to one of a plurality of partdescriptors in a part information table; advancing the predeterminedplay order for a subset of said plurality of track information entriesthat follow said track to be deleted in said predetermined play order soas to account for a removal of said track to be deleted from saidpredetermined play order; reading the one of a plurality of partdescriptors that corresponds to said pointer information in said trackdescriptor; separating in a file system a data block that is a part of afile specified by part pointer information in said part descriptor fromsaid file managed by the file system and freeing said data block on saidfile system, said part pointer information pointing to a part of thefile that includes a plurality of data blocks; freeing said partdescriptor on said file system; and freeing said track descriptor onsaid file system. 2 A track management method according to claim 1,wherein: said file is managed by a file allocation table (FAT) system inFAT cluster units, said method further comprising the step of separatingsaid data block associated with said track to be deleted from said fileon said FAT system and freeing said data block on said FAT system whensaid data block associated with said track to be deleted does not sharea FAT cluster with a data track associated with another track. 3 A trackmanagement method according to claim 2, further comprising the step of:searching the other part descriptor and adjusting said part pointerinformation that points to another data block after said data block whena middle data block in a middle of said file is separated from said fileand freed on said FAT system. 4 A track management method according toclaim 2, wherein: said part pointer information in said part descriptorhas a start address and an end address pointing to said part of saidfile, said method further comprising the step of, separating from saidfile said data block as said part of said file based on said startaddress and said end address and freeing said data block on said FATsystem. 5 A track management method according to claim 2, furthercomprising the steps of: reading a part descriptor corresponding to saidlink information when said part descriptor has link information pointingto a consecutive part descriptor, and separating from said file a datablock associated with said part pointer information in said partdescriptor and freeing said data block on said FAT system when said partdescriptor has link information pointing to said consecutive partdescriptor.
 6. A track management method according to claim 1, wherein:said part pointer information is an offset value from a beginning ofsaid file in predetermined data units. 7 A track management methodaccording to claim 1, wherein: said part pointer information is one of acluster number in a file allocation table system and a physical addressof a storage medium. 8 A track management method according to claim 1,wherein: said file comprises audio data.
 9. A track management apparatuscomprising: first obtaining means for obtaining track information from aplay order table having a plurality of track information entriesarranged in a predetermined play order, said track information points toa track descriptor in a track information table for a track to bedeleted; second obtaining means for obtaining the track descriptor fromthe track information table, said track descriptor including adecryption key corresponding to the track to be deleted and pointerinformation that points to one of a plurality of part descriptors in apart information table; advancing means for advancing the predeterminedplay order of a subset of said plurality of track information entriesthat follow said track to be deleted in said predetermined play order soas to account for a removal of said track to be deleted from saidpredetermined play order; reading means for reading the one of aplurality of part descriptors that corresponds to said pointerinformation in said track descriptor; first means for separating in afile system a data block as a part of a file specified by part pointerinformation in said part descriptor from said file managed by the filesystem and freeing said data block on said file system, said partpointer information pointing to a part of the file having a plurality ofdata blocks; second means for freeing said part descriptor on said filesystem; and third means for freeing said track descriptor on said filesystem. 10 A track management apparatus according to claim 9, whereinsaid file is managed by a file allocation table (FAT) system in FATcluster units, said first means, when said data block associated withsaid track to be deleted does not share a FAT cluster with a data trackassociated with the other track, separates said data block associatedwith said track to be deleted from said file on said FAT system andfrees said data block on said FAT system. 11 A track managementapparatus according to claim 10, further comprising: adjusting meansfor, when a data block of a middle of said file is separated from saidfile and freed on said FAT system, searching the other part descriptorand adjusting said part pointer information pointing to a data blockafter said data block. 12 A track management apparatus according toclaim 10, wherein: said part pointer information in said part descriptorhas a start address and an end address pointing to said part of saidfile; said first means for separating from said file said data block assaid part of said file based on said start address and said end addressand freeing said data block on said FAT system. 13 A track managementapparatus according to claim 10, wherein: said first means, when saidpart descriptor has link information pointing to a consecutive partdescriptor, reads a part descriptor corresponding to said linkinformation, and separates from said file a data block associated withsaid part pointer information in said part descriptor and frees saiddata block on said FAT system.
 14. A track management apparatusaccording to claim 9, wherein: said part pointer information is anoffset value from the beginning of said file in predetermined dataunits. (data block/sound frame) 15 A track management apparatusaccording to claim 9, wherein: said part pointer information is at leastone of a cluster number in a file allocation table system and a physicaladdress of a storage medium. 16 A track management apparatus accordingto claim 9, wherein: said file comprises audio data.